From Longman Dictionary of Contemporary Englishnot exactlynot exactlyspoken a) WRONG/INCORRECTused as a reply to show that what someone has said is not completely correct or true ‘You hate Lee, don’t you?’ ‘Not exactly. I just think he’s a bit annoying, that’s all.’ b) NOTused to show that you mean the complete opposite, either humorously, or when you are annoyed SYN hardly I wouldn’t bother asking Dave – he’s not exactly Einstein (=he is stupid). → exactly
Examples from the Corpus
not exactly• Well, they didn't exactly rush over to help us.• It is not exactly arcane knowledge.• Rebecca Lobo may be off globetrotting with the Olympic team, but the cupboard down there in Storrs is not exactly bare.• Everything, it says, is not exactly crystal clear.• What they're doing is not exactly dishonest, but it's not completely honest either.• I wouldn't bother asking Dave -- he's not exactly Einstein.• She's not exactly fat, but she is slightly overweight.• Her tone was not exactly friendly, but its harshness was of bemused disbelief rather than jealous suspicion.• With a mouth like that, she's not exactly going to fade into the background is she?• The publicity may not exactly have gone to his head but it certainly set fire to his ambition.• "Dan's spent about a million dollars fixing up his house." "Not exactly. It was just a few thousand."• I was already being patient with the way he smelled, not exactly like the perfume department.• But, with a few exceptions, they are not exactly rousing. 