A person who makes themselves look better by insulting and belittling the achievements or problems of others in a derogatory way, at the same time usually not actually contributing anything of use themselves.

Comes from a combination of the British English slang term slag off, meaning to insult or disparage, and braggart, meaning a boastful person.

Slaggarts are unusually common in a number of academic settings, which may be attributed to the immaturity of students and/or staff.
Marty was talking shit about the rest of the football team as if he was carrying the whole team. Like he's so great himself. Fucking slaggart.
by Stealthycat June 24, 2010
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