You may be glad you have an alibi if you’re hauled into court, but you may not want one if you’re merely called on the carpet. When used as a noun in its nonlegal sense of “an excuse,” alibi splits the Usage Panel in half. Forty-nine percent accept it in the sentence He always had a ready alibi for the quality of his service. When alibi is used as an intransitive verb meaning “to make excuses,” as in If you must alibi, at least try to be convincing, it is unacceptable to 72 percent of the panel.