noun, na-adjective, noun which may take the genitive case particle 'no'
coward; weakling; scaredy-cat; wimp
A mildly derogatory term for someone who is timid, easily frightened, or lacks courage. Often used in teasing or self-deprecation. Can function as a noun or adjectival noun.
彼は弱虫だから、ホラー映画は絶対に見ない。
He's such a scaredy-cat that he never watches horror movies.
I want to change my cowardly self.
弟を弱虫呼ばわりするのはやめなさい。
Stop calling your little brother a wimp.