Source : Webster's Revised Unabridged Dictionary (1913)

Summon \Sum"mon\, v. t. [imp. & p. p. {Summoned}; p. pr. & vb.
   n. {Summoning}.] [OE. somonen, OF. sumundre, semondre, F.
   semondre, from (assumed) LL. summon[e^]re, for L.
   summon[=e]re to give a hint; sub under + monere to admonish,
   to warn. See {Monition}, and cf. {Submonish}.]
   1. To call, bid, or cite; to notify to come to appear; --
      often with up.

            Stiffen the sinews, summon up the blood. --Shak.

            Trumpets summon him to war.           --Dryden.

   2. To give notice to, or command to appear, as in court; to
      cite by authority; as, to summon witnesses.

   3. (Mil.) To call upon to surrender, as a fort.

   Syn: To call; cite; notify; convene; convoke; excite; invite;
        bid. See {Call}.

Source : WordNet®

summon
     v 1: call in an official matter, such as to attend court [syn: {summons},
           {cite}]
     2: ask to come; "summon a lawyer"
     3: gather or bring together; "muster the courage to do
        something"; "she rallied her intellect"; "Summon all your
        courage" [syn: {muster}, {rally}, {come up}, {muster up}]
     4: make ready for action or use; "marshal resources" [syn: {mobilize},
         {mobilise}, {marshal}]