vain

for no purpose; [done] as a failure. They rushed her to the hospital, but they did it in vain. We tried in vain to get her there on time.

overly proud; vain. (*Also: as ~.) Mike's been strutting around proud as a peacock since he won that award. I sometimes think Elizabeth must spend all day admiring herself in a mirror. She's as vain as a peacock.

to say someone's name when they are not there, usually when you are criticizing them Did I hear someone taking my name in vain?

To no avail, useless, as in All our work was in vain. [c. 1300] Also see take someone's name in vain.

Having a very high opinion of oneself, filled with or showing excessive self-esteem. For example, She strutted about in her new outfit, proud as a peacock. This simile alludes to the male peacock, with its colorful tail that can be expanded like a fan, which has long symbolized vanity and pride. Chaucer used it in The Reeve's Tail: "As any peacock he was proud and gay." [1200s]

Speak casually or idly of someone, as in There he goes, taking my name in vain again. This idiom originated as a translation from the Latin of the Vulgate Bible (Exodus 20:7), "to take God's name in vain," and for a time was used only to denote blasphemy and profanity. In the early 1700s it began to be used more loosely as well.