Vain or Vane?
Your choice!
Vain
Exemple : ‘’I tried in vain to finish my work on time.’’
The words "vain" and "vane" are commonly confused as they are homonyms. "Vain" can be used to mean "fruitless" or "conceited." It can also be used as "in vain" meaning "without success."
Vane
Exemple : ‘’The weathervane showed that rain was on the way.’’
The noun "vane" is used to denote a part of a fan or a propellor in fairly technical language.