If you deflate someone or something, you take away their confidence or make them seem less important.
e.g. Like any actor he can be self-centred but I think I've worked out how to deflate him...
e.g. Britain's other hopes of medals were deflated earlier in the day.
When she refused I felt deflated.
When something such as a tyre or balloon deflates, or when you deflate it, all the air comes out of it.
e.g. When it returns to shore, the life-jacket will deflate and revert to a harness...
e.g. ...a deflated dinghy.