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.