cowardice

coward | American Dictionary

coward
noun[ C ]
 disapprovingus/ˈkɑʊ·ərd/
person who is not brave, is easily frightened, or tries to avoid danger or difficulties:
A coward is someone who sends you a nasty letter without signing it.

cowardly

adjective[ not gradable ]us/ˈkɑʊ·ərd·li/
disapproving
a cowardly act