weak sister

noun

, Informal.

1. a vacillating person; coward.
2. a part or element that undermines the whole of something; a weak link.

weak sister

noun

1. informal.
   a person in a group who is regarded as weak or unreliable

Word History and Origins

Origin of weak sister¹

First recorded in 1855–60

Example Sentences

To people in Sandy Hook, "Trump comes across as a leader. This fellow, Biden, he comes across as a weak sister," Mr Kinner said.

From BBC

“You could look at him and size him up as the weak sister,” White observed.

From Literature

This is Ethan, who, I’m afraid, turns out to be something of a weak sister, going all shaky on the second date after Nikki smashes in the teeth and breaks the arm of a would-be mugger.

From Washington Post

I was just being a weak sister.

From Literature

You don't want a weak sister in there, nor do you want for one course to offer amenities or an experience that shouts down the other two.

From Golf Digest