1 smirk, curl one's lip, sniff:
Don't sneer - you might be the next to lose your job.
2 scorn, disdain, despise, contemn, turn up one's nose (at), sniff (at), jeer (at), laugh (at), deride, mock, ridicule; underrate; Colloq sneeze at, Slang knock:
They sneered at her ambition to become a serious athlete.
3 scorn, jeer, disdain, contempt, derision, mockery, ridicule; sneering, jeering:
Barry endured his classmates' sneers without a word.