chickenshit

Short definition from Wiktionary

Adjective

1. 1
   Petty; contemptibly unimportant. (Compare bullshit.)
2. 2
   Cowardly.

Noun

1. 1
   A petty and contemptible thing or things.
2. 2
   A coward.
3. 3
   A low-ranking officer who lords over and needlessly makes life miserable for his underlings; a petty, abusive martinet.
4. 4
   Used other than figuratively or idiomatically: see chicken, shit: chicken manure.