We have the Slang word: • Ain’t 1. in. is not. (Colloquial. Stigmatized, jocular, mock undereducated, as well as undereducated use. Its use is widespread and sometimes deliberate in educated spoken use and when writing for effect. Properly an old contraction of am not or are not. The battle against ain’t was lost at least two centuries ago but is still fought in isolated areas. See also If it ain’t broke don’t fix it.; If it ain’t broke, fix it till it is.; That ain’t hay!; There ain’t no such thing as a free lunch.) - Saying “Ain’t ain’t in the dictionary” ain’t so.