An example of a sneer is a mocking smile that someone makes that shows his contempt.
An example of to sneer is when you give someone a mocking smile as you make fun of them.
To sneer fulsome lies at a person.
Origin of sneer
- From Middle English sneren to mock alteration of Old English fnǣran to breathe heavily pneu- in Indo-European roots
From American Heritage Dictionary of the English Language, 5th Edition