Source : Webster's Revised Unabridged Dictionary (1913)

Interest \In"ter*est\, v. t. [imp. & p. p. {Interested}; p. pr.
   & vb. n. {Interesting}.] [From interess'd, p. p. of the older
   form interess, fr. F. int['e]resser, L. interesse. See
   {Interest}, n.]
   1. To engage the attention of; to awaken interest in; to
      excite emotion or passion in, in behalf of a person or
      thing; as, the subject did not interest him; to interest
      one in charitable work.

            To love our native country . . . to be interested in
            its concerns is natural to all men.   --Dryden.

            A goddess who used to interest herself in marriages.
                                                  --Addison.

   2. To be concerned with or engaged in; to affect; to concern;
      to excite; -- often used impersonally. [Obs.]

            Or rather, gracious sir, Create me to this glory,
            since my cause Doth interest this fair quarrel.
                                                  --Ford.

   3. To cause or permit to share. [Obs.]

            The mystical communion of all faithful men is such
            as maketh every one to be interested in those
            precious blessings which any one of them receiveth
            at God's hands.                       --Hooker.

   Syn: To concern; excite; attract; entertain; engage; occupy;
        hold.

Interest \In"ter*est\, n. [OF. interest, F. int['e]r[^e]t, fr.
   L. interest it interests, is of interest, fr. interesse to be
   between, to be difference, to be importance; inter between +
   esse to be; cf. LL. interesse usury. See {Essence}.]
   1. Excitement of feeling, whether pleasant or painful,
      accompanying special attention to some object; concern.

   Note: Interest expresses mental excitement of various kinds
         and degrees. It may be intellectual, or sympathetic and
         emotional, or merely personal; as, an interest in
         philosophical research; an interest in human suffering;
         the interest which an avaricious man takes in money
         getting.

               So much interest have I in thy sorrow. --Shak.

Source : WordNet®

interest
     v 1: excite the curiosity of; engage the interest of [ant: {bore}]
     2: be on the mind of; "I worry about the second Germanic
        consonant" [syn: {concern}, {occupy}, {worry}]
     3: be of importance or consequence; "This matters to me!" [syn:
         {matter to}]

interest
     n 1: a sense of concern with and curiosity about someone or
          something; "an interest in music" [syn: {involvement}]
     2: the power of attracting or holding one's interest (because
        it is unusual or exciting etc.); "they said nothing of
        great interest"; "primary colors can add interest to a
        room" [syn: {interestingness}] [ant: {uninterestingness}]
     3: a reason for wanting something done; "for your sake"; "died
        for the sake of his country"; "in the interest of safety";
        "in the common interest" [syn: {sake}]
     4: a fixed charge for borrowing money; usually a percentage of
        the amount borrowed; "how much interest do you pay on your
        mortgage?"
     5: a diversion that occupies one's time and thoughts (usually
        pleasantly); "sailing is her favorite pastime"; "his main
        pastime is gambling"; "he counts reading among his
        interests"; "they criticized the boy for his limited
        pursuits" [syn: {pastime}, {pursuit}]
     6: (law) a right or legal share of something; a financial
        involvement with something; "they have interests all over
        the world"; "a stake in the company's future" [syn: {stake}]
     7: (usually plural) a social group whose members control some
        field of activity and who have common aims; "the iron
        interests stepped up production" [syn: {interest group}]