Slang: Wuss

Definition: A coward; an ineffectual, timid person.

Example:

1) Don't be a wuss, Stephan. It's just a little spider! 

2) You're afraid of the dark? What are you, some kind of wuss?

Etymology: This word has been popular with teenage boys since the 1960's.

Synonyms: wimp, sissy

fonte: www.peakenglish.com