"We let them know in very strong terms that they were wrong."
She let me know in no uncertain terms that everything was all right between us.
Here you always knew, in concrete terms: this for that.
But even a child of three or four is old enough to know in simple terms what's happening.
I let him know in no uncertain terms that promoting you would be a criminal act.
He was fairly sure he knew the answer, at least in general terms.
You praise people for doing well and let them know in no uncertain terms when they haven't.
You have to let him know in no uncertain terms that his behaviour is not appropriate.
"He let me know in no uncertain terms what he was thinking," she said.
When she didn't do something exactly as he'd told her, he let her know about it in unmistakable terms.