Source : Webster's Revised Unabridged Dictionary (1913)

Chap \Chap\ (ch[a^]p), n. [Perh. abbreviated fr. chapman, but
   used in a more general sense; or cf. Dan. ki[ae]ft jaw,
   person, E. chap jaw.]
   1. A buyer; a chapman. [Obs.]

            If you want to sell, here is your chap. --Steele.

   2. A man or boy; a youth; a fellow. [Colloq.]

Chap \Chap\ (ch[a^]p or ch[o^]p), v. t. [imp. & p. p. {Chapped}
   (ch[a^]pt or ch[o^]pt); p. pr. & vb. n. {Chapping}.] [See
   {Chop} to cut.]
   1. To cause to open in slits or chinks; to split; to cause
      the skin of to crack or become rough.

            Then would unbalanced heat licentious reign, Crack
            the dry hill, and chap the russet plain.
                                                  --Blackmore.

            Nor winter's blast chap her fair face. --Lyly.

   2. To strike; to beat. [Scot.]

Chap \Chap\, v. i.
   1. To crack or open in slits; as, the earth chaps; the hands
      chap.

   2. To strike; to knock; to rap. [Scot.]

Chap \Chap\, v. i. [See {Cheapen}.]
   To bargain; to buy. [Obs.]

Chap \Chap\, n. [From {Chap}, v. t. & i.]
   1. A cleft, crack, or chink, as in the surface of the earth,
      or in the skin.

   2. A division; a breach, as in a party. [Obs.]

            Many clefts and chaps in our council board. --T.
                                                  Fuller.

   3. A blow; a rap. [Scot.]

Chap \Chap\ (ch[o^]p), n. [OE. chaft; of Scand. origin; cf. Icel
   kjaptr jaw, Sw. K["a]ft, D. ki[ae]ft; akin to G. kiefer, and
   E. jowl. Cf. {Chops}.]
   1. One of the jaws or the fleshy covering of a jaw; --
      commonly in the plural, and used of animals, and
      colloquially of human beings.

            His chaps were all besmeared with crimson blood.
                                                  --Cowley.

            He unseamed him [Macdonald] from the nave to the
            chaps.                                --Shak.

   2. One of the jaws or cheeks of a vise, etc.

Source : WordNet®

chap
     v : crack due to dehydration; "My lips chap in this dry weather"
     [also: {chapping}, {chapped}]

chap
     n 1: a boy or man; "that chap is your host"; "there's a fellow at
          the door"; "he's a likable cuss" [syn: {fellow}, {feller},
           {lad}, {gent}, {fella}, {blighter}, {cuss}]
     2: a long narrow depression in a surface [syn: {crevice}, {cranny},
         {crack}, {fissure}]
     3: a crack in a lip caused usually by cold
     4: (usually in the plural) leather leggings without a seat;
        joined by a belt; often have flared outer flaps; worn over
        trousers by cowboys to protect their legs
     [also: {chapping}, {chapped}]

Source : Free On-Line Dictionary of Computing

CHAP
     
        {Challenge-Handshake Authentication Protocol}