(deyim) Lit. [for something] to release steam: The locomotive let off some steam after it came to a halt. With a great hiss, it let off steam and frightened the children
(deyim) to do or say something that helps you to get rid of strong feelings or energy: Meetings give people the chance to let off steam if something has been bothering them for a long time. After a long journey, the kids need to run around a bit and let off steam. I've told her she can call me and talk any time she wants to blow off steam
(deyim) Fig. to release one's pent-up emotions, such as anger, usually verbally: I'm sorry I yelled at you. I guess I needed to let off some steam. She's not that mad. She's just letting off steam