transitive verb. 1 : to tighten, fasten, or lock by or as if by a screw. 2a : bungle, botch. b : to cause to act or function in a crazy or confused way : confound, disturb.

What does it mean to be called a screw up?

a situation in which you do something badly or make a big mistake: There's been a screw-up with our hotel reservation.

Is it rude to say screw up?

It is definitely rude if you say it toward a person, esp. like "screw you" = "f-you" It is not really rude to say "screwed up" - that's common (casual) speech, unless you're talking with somebody who's unusually sensitive.