- (intransitive, transitive) To open.
- Some vacancies have opened up due to retirements.
- Open up the door!
- 2011 February 1, Phil McNulty, “Arsenal 2 - 1 Everton”, in BBC:
- Wilshere then opened up Everton's defence, but Van Persie lifted his finish over the onrushing Howard and also over the bar.
- (intransitive) To reveal oneself; to share personal information about oneself; to become communicative.
- After three hours of questioning, he finally opened up.
- (intransitive) To commence firing weapons.
- As the convoy entered the pass, we opened up on them with everything we had.
- (intransitive, figuratively, of the sky) To rain.
- The sky has really opened up. I've never seen this much rain!