1 [uncountable and countable] the opinion or feeling you have about someone or something because of the way they seem COLLOCATIONS 
give/create/convey an impression leave somebody with an impression leave an impression (on somebody) have/get the impression (that) make an impression (on somebody) (=make someone admire or remember you) first/initial impression (=the impression you get when you see someone or something for the first time) good/favourable impression bad impression false/wrong/misleading impression lasting/indelible impression overall/general impression the distinct impression (that)

give/create/convey an impression leave somebody with an impression leave an impression (on somebody) have/get the impression (that) make an impression (on somebody) (=make someone admire or remember you) first/initial impression (=the impression you get when you see someone or something for the first time) good/favourable impression bad impression false/wrong/misleading impression lasting/indelible impression overall/general impression the distinct impression (that)
2 to believe that something is true when it is not :
I'm sorry, I was under the impression that you were the manager.
be under the impression (that)
I'm sorry, I was under the impression that you were the manager.3 [countable] when someone copies the speech or behaviour of a famous person in order to make people laugh [= imitation]:
4 [countable] a picture or drawing of what someone or something might look like, or what something will look like in the future
5 [countable] a mark left by pressing something into a soft surface :
6 [countable]TCN all the copies of a book printed at one time [↪ edition]

Related topics: