tilt at windmills
to waste time and energy attacking an enemy that is not real

[TahlilGaran] Dictionary of Contemporary English ▲

tilt at windmills
[literary]
to waste time trying to deal with enemies or problems that do not exist.
We're not tilting at windmills here. If we don't do something about these problems, our environment may be in serious danger.

[TahlilGaran] English Idioms Dictionary ▲

tilt at windmills
to fight battles with imaginary or unimportant enemies or issues
My friend is tilting at windmills by fighting his boss for no reason.

[TahlilGaran] English Idioms Dictionary ▲

tilt at windmills
v. phr., literary To do battle with an imaginary foe (after Cervantes' Don Quixote).
John is a nice guy but when it comes to departmental meetings he wastes everybody's time by constantly tilting at windmills.

[TahlilGaran] English Idioms Dictionary ▲