The Collaborative International Dictionary of English v.0.48:

Subpoena \Sub*poe"na\, n. [NL., fr. L. sub under + poena
   punishment. See Pain.] (Law)
   A writ commanding the attendance in court, as a witness, of
   the person on whom it is served, under a penalty; the process
   by which a defendant in equity is commanded to appear and
   answer the plaintiff's bill. [Written also subpena.]
   [1913 Webster]

   Subpoena ad testificandum. [NL.] A writ used to procure the
      attendance of a witness for the purpose of testifying.

   Subpoena duces tecum. [NL.] A writ which requires a witness
      to attend and bring certain documents.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Subpoena \Sub*poe"na\, v. t. [imp. & p. p. Subpoenaed; p. pr.
   & vb. n. Subpoenaing.] (Law)
   To serve with a writ of subpoena; to command attendance in
   court by a legal writ, under a penalty in case of
   disobedience.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

44 Moby Thesaurus words for "subpoena":
   bid come, call, call away, call back, call for, call forth,
   call in, call out, call together, call up, certiorari, citation,
   cite, conjure, conjure up, convene, convoke, demand, evoke,
   garnishment, habeas corpus, indent, invoke, monition, muster,
   muster up, order up, page, preconize, recall, requisition,
   send after, send for, serve, summon, summon forth, summon up,
   summons, venire, venire de novo, venire facias, warrant, writ,
   writ of summons