Green’s Dictionary of Slang

1. an unpleasant, prying person.

1916

G. Jennings Poached Eggs and Pearls (1917) 16: lady mabel: Look at Lady Penzance giving him the glad eye! lady clara: The snark! She’ll watch me like a lynx.

2. an informer.

1962

Ragen & Finston World’s Toughest Prison 818: snark – An informer.

3. anger, irritation, tetchiness; sarcasm.

2002		D.H. Sterry Chicken (2003) 132: Some serious snark is clogging my pipes. I want to smash a mirror with a five-iron, crack a skull with a brick.
2009		J. Stahl Pain Killers 150: Trying to exude impassive blandness in the face of her snark.
2013		T. Robinson Hard Bounce [ebook] He didn’t bite at my snark.