1.NounSynonym of know-it-all, an obnoxious clever person or a person making obnoxious efforts to seem clever by acting or behaving as if they know everything.
2.NounAn insolent person, especially one who makes snide remarks.
"Lots of luck, smartass."
3.AdjectiveRelated to or characteristic of a smartass; irritatingly clever or smug.
"I have had quite enough of your smartass remarks."
4.VerbTo talk like a smartass, with a lot of snide remarks.