- (transitive) to prevent from entering or penetrating.
- High-factor suncream blocks out the sun's rays.
- (idiomatic, transitive) to prevent (a thought) from entering one's mind.
- After finding out she had terminal cancer, she tried to block out any thoughts of her own mortality.
- (transitive) to cover something, so as to make it impossible to see.
- (transitive) to begin to reduce to shape; to mark out roughly; to lay out.
- to block out a plan