1. verb, rude slang To do something halfheartedly or without one's full effort. Did you half-ass these posters? There's a bunch of misspellings, and the ink is all smudged.

2. adjective, rude slang Describing something that has been done halfheartedly or without one's full effort. Also seen as "half-assed." It was just a half-ass attempt, so naturally it didn't work. Look at these half-assed posters—there's a bunch of misspellings, and the ink is all smudged.