Agreement or concord happens when a word changes form depending on the other words to which it relates. It is an instance of inflection, and usually involves making the value of some grammatical category "agree" between varied words or parts of the sentence.
When a compound subject contains both a singular and a plural noun or pronoun joined by "or" or "nor," the verb should agree with the part of the subject that is closest to the verb. This is also called the rule of proximity. Example: The student or the committee members write every day.
