cowardly       
adjective uk/ˈkaʊ.əd.li/ us/ˈkaʊ.ɚd.li/
B2 怯懦地
in a way that is not at all brave and tries to avoid danger
  This was a particularly brutal and cowardly attack. 这是一次特别残忍和懦弱的攻击。 
 They are guilty of a cowardly failure to address the problem. 他们因懦弱而未能解决问题,为此感到内疚。 
 Synonyms: chicken craven fainthearted lily-livered pusillanimous timidweak-kneed yellow (NOT BRAVE) 
See: coward
 - More examples
 - He was too cowardly to give us the order.
 - He said he was the victim of a cowardly campaign of character assassination.
 - Their failure to ask tough questions and hold their leaders to account is cowardly in the extreme.