a boy who other boys dislike and laugh at because they think he is weak or interested in activities girls usually like, or a person who is weak and cowardly (= not brave)

Kevin is such a sissy. 凯文真是个娘娘腔。

[ as form of address ] Can't you climb that tree, you big sissy? 你爬不上那棵树吧，你这个胆小鬼！