(dissenting). The issue in this case is whether the proof of “cohabitation” submitted by Mr. Graev was adequate to discontinue his maintenance obligation under the cohabitation clause in the parties’ agreement. I conclude it was and, therefore, would hold, as matter of law, that Mr. Graev is entitled to terminate his maintenance payments. The majority, *275however, views the use of the term “cohabitation” in the divorce settlement agreement in this case as inherently ambiguous and requires a court to make findings of fact regarding what the parties intended the term to mean. Because the cohabitation provision includes a specific time period together with the maintenance termination event, I believe the clause is unambiguous and there is no need to remit this case to Supreme Court for yet another hearing.
I
After two years of contentious divorce litigation, the Graevs negotiated a settlement agreement, which was incorporated, but not merged, in the judgment of divorce entered in June 1997. According to the terms of the negotiated settlement, Lawrence Graev paid Linda Graev almost $2.5 million and agreed to make maintenance payments of $120,000 a year (later increased to $132,000 a year), with monthly maintenance payments continuing until August 10, 2009—about 12 years after the parties’ divorce. These payments would terminate upon the occurrence of one of four specified events: (1) the death of Mrs. Graev; (2) the death of Mr. Graev; (3) Mrs. Graev’s remarriage; or (4) Mrs. Graev’s “cohabitation . . . with an unrelated adult for a period of sixty (60) substantially consecutive days.”1
Linda Graev’s primary residence was an apartment on Fifth Avenue in New York City, but she also maintained a home in Connecticut that she used intermittently and for about two months every summer. Sometime after the divorce, she became acquainted with M.E, who owned a home near hers in Connecticut. They soon began an exclusive and intimate relationship. It is undisputed that M.E and Mrs. Graev spent virtually every day and night together for over 60 days from June through August 2004. M.E had unfettered access to her home, but he did not keep much personal property at Mrs. Graev’s house (with the exception of an approximately two-week period after he sold his home and before he purchased a new house). Each paid for their own expenses and their finances were not commingled. Despite M.E’s daily use of Mrs. Graev’s home, he did not make contributions toward upkeep of the property. As Mrs. Graev’s *276constant companion, M.E began attending Graev family functions, such as birthday and college graduation celebrations. In fact, when M.E attended the Graevs’ daughter’s wedding ceremony, he joined in the formal family photographs that were taken to commemorate that occasion.
After receiving reports from investigators regarding M.E’s consistent presence at his ex-wife’s home, Lawrence Graev moved to terminate his maintenance obligation on the ground that Linda Graev had cohabitated with M.E during the summer of 2004. She countered that she had not triggered a spousal support termination event because M.E owned a home and their finances remained separate. Both Supreme Court and the Appellate Division concluded that there was no cohabitation under the meaning of the parties’ divorce agreement because Mrs. Graev and M.E did not function as a single “economic unit.” Mr. Graev now appeals to this Court as of right on the basis of a two-Justice dissent in the Appellate Division that would have granted his application on the rationale that financial interdependence is not a prerequisite to cohabitation.
II
“A separation agreement is a contract subject to the principles of contract construction and interpretation” (Matter of Meccico v Meccico, 76 NY2d 822, 823-824 [1990]). It is an elementary rule that contracts are construed in accordance with the intent of the parties and the best evidence of the parties’ intent is what they write in their agreement (see e.g. Goldman v White Plains Ctr. for Nursing Care, LLC, 11 NY3d 173, 176 [2008]). Consequently, if a written agreement is complete, clear and unambiguous, it “ ‘must be enforced according to the plain meaning of its terms,’ without reference to extrinsic materials outside the four corners of the document” (id., quoting Greenfield v Philles Records, 98 NY2d 562, 569 [2002]). When presented with such an agreement, “a court is not free to alter the contract to reflect its personal notions of fairness and equity” (Greenfield v Philles Records, 98 NY2d at 570).
Contrary to the majority’s assertion, I find that the term “cohabitation” has a commonly-accepted core meaning: habitually living with an unrelated adult in the same residence while engaged in an intimate relationship without being legally married to that person (see e.g. Black’s Law Dictionary 277 [8th ed] [“The fact or state of living together, esp. as partners in life, *277usu. with the suggestion of sexual relations”]; New Oxford American Dictionary 330 [2d ed 2005] [“live together and have a sexual relationship without being married”]; Random House Webster’s Unabridged Dictionary 400 [2d ed 2001] [“1. to live together as husband and wife, usually without legal or religious sanction. 2. to live together in an intimate relationship”]; Webster’s Third New International Dictionary 440 [2002 ed] [“to live together as or as. if as husband and wife”]). In fact, we have explained that “cohabitation” is synonymous with the phrase “habitually living with another” person for purposes of the maintenance termination provisions of Domestic Relations Law § 248 (see e.g. Matter of Bliss v Bliss, 66 NY2d 382, 389 [1985] [“statutory language clearly mandates discrete findings of cohabitation and holding out” (emphasis added)]; Northrup v Northrup, 43 NY2d 566, 571 [1978]; see also Markhoffv Markhoff, 225 AD2d 1000, 1001 [3d Dept 1996], lv denied 88 NY2d 807 [1996]; Gordon v Gordon, 342 Md 294, 297 n 2, 675 A2d 540, 542 n 2 [1996]; E.D.M. v T.A.M., 307 SC 471, 475, 415 SE2d 812, 815 [1992] [“evidence of living together in an intimate relationship supports a finding of cohabitation”]).
It is true, however, that the use of the term “cohabitation” without elaboration or conditions is capable of causing ambiguity. This is because a living arrangement becomes cohabitation only if it is habitual and this requirement may not be quantified in every situation. But the parties in this case were careful to avoid this pitfall by indicating that the benchmark would be a specific duration—“sixty (60) substantially consecutive days”—a practice that is implicitly recommended by a leading New York treatise (see Scheinkman, New York Law of Domestic Relations, Appendix B, at 550 [12 West’s NY Prac Series] [“openly and continuously cohabits with an unrelated male for a continuous period exceeding 30 days”]). This was sufficient to make the cohabitation clause here unambiguous.2
The Graevs agreed that maintenance payments would terminate if Linda Graev cohabitated for 60 or more substantially consecutive days with a person not related to her. As Mrs. Graev concedes, she and M.P were in an intimate relationship: they held themselves out as a couple to their family, friends and *278community; their approximately three-year relationship was exclusive, monogamous and, at least for a time, sexual in nature; M.E attended family celebrations; he had complete access to her home; they spent most of their time together; and they slept together almost every night for at least 60 substantially consecutive days. Consequently, I would hold that Mrs. Graev cohabitated with M.E for the requisite period of time, resulting in the termination of her right to continued maintenance.
Ill
The fact that Mrs. Graev and M.E lived together intimately for the relevant time frame but did not share household expenses or “function as an economic unit”—the key component of the Appellate Division’s reasoning—does not provide an adequate basis for departing from the text of this divorce agreement and basic principles of contract law. To begin, in construing the term “cohabitation,” we have never suggested that two people cannot “live together” in an intimate relationship if they do not function as an “economic unit” (see e.g. Matter of Bliss v Bliss, 66 NY2d at 389; Northrup v Northrup, 43 NY2d at 571). Admittedly, there is a line of Appellate Division cases that supports the idea that cohabitation requires financial interdependence. The genesis of this analysis appears to have been Scharnweber v Scharnweber (105 AD2d 1080 [4th Dept 1984], affd 65 NY2d 1016 [1985]). The agreement in that case specified that the ex-wife would “not have any unrelated male living in the household” that was the former marital residence. The Appellate Division concluded that this condition had not been met because the ex-wife and the new man did “not share household expenses or a bedroom and d[id] not function as an economic unit” (id.).
This Court affirmed, noting only that the evidence failed to establish that “the wife lived with an unrelated male at the former marital residence” (65 NY2d at 1017). Significantly, we did not address or endorse the “economic unit” requirement. Nevertheless, courts have subsequently adopted the notion that cohabitation requires a sharing of household expenses or functioning as an economic unit without adequately explaining why this factor must be engrafted on divorce agreements and stipulations that do not incorporate such a condition (see e.g. Clark v Clark, 33 AD3d 836 [2d Dept 2006]; Matter of Ciardullo v Ciardullo, 27 AD3d 735 [2d Dept 2006]).
*279Today, as a Court, we unanimously reject the rule that economic interdependence is a sine qua non of cohabitation.3 Aside from the textual and contractual considerations, that rule makes little sense practically because a party receiving maintenance can easily evade the consequence of a termination provision and receive more than the benefit of his or her bargain. Mrs. Graev and M.E, for example, would be free to continue their relationship in its current form indefinitely without violating the termination provision—they could be together 24 hours a day and sleep together every night for years—but as long as they maintain separate bank accounts and do not share expenses, they would not be cohabitating under the economic unit concept. This is not how a cohabitation clause is supposed to work; nor is it what other parties anticipate when including similar cohabitation clauses in their agreements.
That being said, I agree with the majority that economic interdependence can be relevant to the cohabitation analysis. As the plain meaning of the term makes clear, cohabitation is comprised of several distinct elements: (1) living with (2) an unrelated adult (3) for a specified period of time or with an expectation of permanence (4) in an intimate relationship (5) without being married to that person. In my view, the extent to which a couple intermingles its finances is pertinent on the issues of whether the relationship is sufficiently “intimate” or whether the parties intended a long-term commitment. But in this case, the intimate nature of the relationship is not in dispute, and the question of duration or permanence is addressed by the agreement itself—60 substantially consecutive days. Hence, the cohabitation clause has been triggered.
The Appellate Divisions’ “economic unit” theory is also undermined by its failure to take into account that financial independence, as well as economic interdependence, may sometimes support a finding of cohabitation. This is so because there can be more than one purpose for a cohabitation clause. It can represent the parties’ understanding that one ex-spouse should *280not have to pay maintenance if the other has a new partner to help support his or her lifestyle. But, just as importantly, these clauses may also be designed to prevent an ex-spouse from using the money he or she receives from an ex-spouse to support a new paramour.4
IV
In sum, the majority’s determination that the use of “cohabitation” in divorce agreements gives rise to ambiguity raises serious concerns. First, it will create a proliferation of litigation in virtually every case where these commonly-used cohabitation/ maintenance termination provisions are sought to be enforced. And courts, in turn, will have little helpful evidence when attempting to evaluate the issue other than the self-interested testimony of the parties themselves.5 Second, requiring extrinsic evidence in all these cases undermines the primary purpose for entering into written agreements—to memorialize the parties’ understanding of the parameters of permissible and impermissible conduct and personal relations. Thus, the majority’s rule creates uncertainty, making it difficult for parties to understand their obligations and responsibilities. The wiser choice is to articulate a clear rule of law: cohabitation occurs when two unrelated adults who are not married to each other have an intimate relationship and live together habitually for an agreed-to period of time.
For all of these reasons, I conclude that the maintenance obligation was terminated by operation of the cohabitation *281clause and would hold that Lawrence Graev is entitled to judgment as a matter of law.
Chief Judge Kaye and Judges Ciparick and Jones concur with Judge Read; Judge Graffeo dissents in a separate opinion in which Judges Smith and Pigott concur.
Order reversed, etc.
. The agreement here did not incorporate the entire statutory standard set forth in Domestic Relations Law § 248 for termination of court-ordered support. Section 248 allows a court, upon application, to exercise discretion “upon proof that the wife is habitually living with another man and holding herself out as his wife, although not married to such man.”
. Although it has been said that “cohabitation,” standing alone, is ambiguous because it can mean to live with a man, a woman, or either a man or a woman (Kripp v Kripp, 578 Pa 82, 92-93, 849 A2d 1159, 1165 [2004]), even if that is true the divorce agreement in this case specified that Mrs. Graev would not live with an unrelated “adult.”
. The essential holding of the majority’s opinion is that there can be cohabitation without financial interdependence or functioning as an economic unit (see majority op at 273 [recognizing the existence of the Appellate Divisions’ “economic unit” theory but stating that “we have never taken this position and decline to do so” in this case]).
. See e.g. Gordon v Gordon, 342 Md at 309-310, 675 A2d at 548 (“if the cohabitant does not pay a fair share of the household expenses, then it follows that part of the support payment supports the cohabitant rather than the ex-spouse”); Wolfe v Wolfe, 46 Ohio St 2d 399, 421, 350 NE2d 413, 427 (1976) (“ ‘if the paramour resides in the wife’s home without contributing anything toward the purchase of food or the payment of normal household bills, then there may be a reasonable inference that the wife’s alimony is being used, at least in part, for the benefit of the paramour, in which case it could be argued with force that the amount thereof should be modified accordingly’ ”), quoting Garlinger v Garlinger, 137 NJ Super 56, 64, 347 A2d 799, 803 (1975).
. Parties to future divorce agreements may wish to consider whether to define “cohabitation” to expressly exclude the “economic unit” concept (see generally Zipparo v Zipparo, 70 AD2d 616 [2d Dept 1979] [defining term to mean “ ‘the regular living together of the Wife with a man for period exceeding six (6) months’ ”]) or simply discontinue using the term “cohabitation”— which the majority believes is inherently meaningless in the absence of factual findings regarding the parties’ intent—in favor of “reside” or “live together” along with a specified period of time.