There are some very real, practical reasons why your contract must be laid out in clear, unambiguous terms: if it's unclear, there is a substantial chance that a New York court won't enforce it.

So, when is a contract - or a clause in a contract considered "ambiguous"?

"An agreement is ambiguous where “a reasonably intelligent person viewing the contract objectively could interpret the language in more than one way.” Id. “To the extent the moving party's case hinges on ambiguous contract language, summary judgment may be granted only if the ambiguities may be resolved through extrinsic evidence that is itself capable of only one interpretation, or where there is no extrinsic evidence that would support a resolution of these ambiguities in favor of the nonmoving party's case.” Id. 

A word of caution is in order, however:

“[T]he mere assertion by a party that contract language means something other than what it clearly says is not sufficient to raise a triable issue of fact.” 239 East 79th Owners Corp. v. Lamb 79 & 2 Corp., 30 A.D.3d 167, 168, 818 N.Y.S.2d 194, 195 (1st Dep't 2006).

In non-legal terms - and at the risk of stating the obvious - this means that you can't defeat a breach of contract claim by simply asserting that the contract is ambiguous; it has to actually be ambiguous.