Definitions of impression:

• noun:   the act of pressing one thing on or into the surface of another

  Example: "He watched the impression of the seal on the hot wax"

• noun:   an impressionistic portrayal of a person

  Example: "He did a funny impression of a politician"

• noun:   (dentistry) an imprint of the teeth and gums in wax or plaster

  Example: "The dentist took an impression for use in preparing an inlay"

• noun:   an outward appearance

  Example: "He made a good impression"

• noun:   a vague idea in which some confidence is placed

  Example: "His impression of her was favorable"

• noun:   all the copies of a work printed at one time
• noun:   a symbol that is the result of printing
• noun:   a concavity in a surface produced by pressing

  Example: "He left the impression of his fingers in the soft mud"

• noun:   a clear and telling mental image

  Example: "The events left a permanent impression in his mind"