Merriam-Webster Collegiate Dictionary - impression

 noun  Date: 14th century  1.  a. a characteristic, trait, or feature resulting from some influence the ~ on behavior produced by the social milieu  b. an effect of alteration or improvement the settlement left little ~ on the wilderness  c. a telling image impressed on the senses or the mind  2. the effect produced by impressing: as  a. a stamp, form, or figure resulting from physical contact  b. an imprint of the teeth and adjacent portions of the jaw for use in dentistry  c. an especially marked and often favorable influence or effect on feeling, sense, or mind  3. the act of impressing: as  a. an affecting by stamping or pressing  b. a communicating of a mold, trait, or character by an external force or influence  4.  a. the amount of pressure with which an inked printing surface deposits its ink on the paper  b. one instance of the meeting of a printing surface and the material being printed; also a single print or copy so made  c. all the copies (as of a book) printed in one continuous operation from a single makeready  5. an often indistinct or imprecise notion or remembrance  6.  a. the first coat of color in painting  b. a coat of paint for ornament or preservation  7. an imitation or representation of salient features in an artistic or theatrical medium; especially an imitation in caricature of a noted personality as a form of theatrical entertainment  Synonyms: see idea