impression

Definition of impression

1an idea, feeling, or opinion about something or someone, especially one formed without conscious thought or on the basis of little evidence:his first impressions of Manchester were very positive I got the impression that he was sorely disappointed
an effect produced on someone:her courtesy had made a good impression
[mass noun] a difference made by the action or presence of someone or something:the floor was too dirty for the mop to make much impression

2an imitation of a person or thing, done to entertain:he did an impression of Shirley Bassey

3a mark impressed on a surface:the impression of his body on the leaves
Dentistry a negative copy of the teeth or mouth made by pressing them into a soft substance.

4a graphic or pictorial representation of someone or something:police issued an artist’s impression of the attacker

5the printing of a number of copies of a book, periodical, or picture for issue at one time.
[usually with modifier] chiefly British a particular printed version of a book, especially one reprinted from existing type, plates, or film with no or only minor alteration: a copy of the first impression
a print taken from an engraving.

6an instance of a pop-up or other Web advertisement being seen on an Internet user’s monitor.

Phrases

under the impression that: believing, mistakenly or on the basis of little evidence, that something is the case:he was under the impression that they had become friends

late Middle English: via Old French from Latin impressio(n-), from impress- 'pressed in', from the verb imprimere (see imprint)

Spell impression and the related word impressive with a double s.

Definition of impression in the US English dictionary