be under the impression that

be under the impression that

To be living, operating, or functioning with the belief that something is true. Jeremy's always been under the impression that he's a great writer, even though he's never written more than a few crummy poems. Oh, I was under the impression that we were meeting at two—did that change?
See also: impression, that

be under the imˈpression that...

believe, usually wrongly, that...: I was under the impression you were coming tomorrow, not today.
See also: impression