To confide (one's thoughts or feelings).
To relieve (oneself) of troublesome thoughts or feelings.
To reveal one's thoughts or feelings.
To give vent to (feelings, secrets, etc.); tell; reveal.
To reveal what one feels, knows, etc.
- to tell or reveal one's feelings, secrets, etc.
Idioms and Phrasal Verbs
Origin of unbosom
- un- +"Ž bosom (“the seat of emotions").