wimp
n. countablen. a person who is weak, cowardly, or lacks confidence. It is a very informal and sometimes rude way to describe someone who won't stand up for themselves.
n. a person perceived as weak, timid, or lacking in courage. Highly informal and often considered derogatory in professional or academic contexts.
He is such a wimp that he won't even go to the dark room.
The kids at school started calling him a wimp because he refused to join their risky game of tag.
Possibly a clipping of whimper. The term was understood in the United States by the 1930s, as it was incorporated into the names of two famous media characters known for living up to that name: The devious but cowardly Popeye supporting-character called "J. Wellington Wimpy", and the soft-spoken character "Wallace Wimple" from the radio show Fibber McGee and Molly.
See WIMP.