The Collaborative International Dictionary of English v.0.48:

Deem \Deem\, v. i.
   1. To be of opinion; to think; to estimate; to opine; to
      suppose.
      [1913 Webster]

            And deemest thou as those who pore,
            With aged eyes, short way before?     --Emerson.
      [1913 Webster]

   2. To pass judgment. [Obs.] --Spenser.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Deem \Deem\ (d[=e]m), v. t. [imp. & p. p. Deemed (d[=e]md); p.
   pr. & vb. n. Deeming.] [OE. demen to judge, condemn, AS.
   d[=e]man, fr. d[=o]m doom; akin to OFries. d[=e]ma, OS.
   ad[=o]mian, D. doemen, OHG. tuommen, Icel. d[ae]ma, Sw.
   d["o]mma, Dan. d["o]mme, Goth. d[=o]mjan. See Doom, n., and
   cf. Doom, v.]
   1. To decide; to judge; to sentence; to condemn. [Obs.]
      [1913 Webster]

            Claudius . . . Was demed for to hang upon a tree.
                                                  --Chaucer.
      [1913 Webster]

   2. To account; to esteem; to think; to judge; to hold in
      opinion; to regard.
      [1913 Webster]

            For never can I deem him less him less than god.
                                                  --Dryden.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Deem \Deem\, n.
   Opinion; judgment. [Obs.] --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

deem
    v 1: keep in mind or convey as a conviction or view; "take for
         granted"; "view as important"; "hold these truths to be
         self-evident"; "I hold him personally responsible" [syn:
         deem, hold, view as, take for]

Moby Thesaurus II by Grady Ward, 1.0:

75 Moby Thesaurus words for "deem":
   account, account as, adjudge, adjudicate, allow, assume, be afraid,
   be judicious, believe, calculate, conceive, conclude, conjecture,
   consider, count, credit, daresay, deduce, divine, dream, esteem,
   estimate, exercise judgment, expect, express an opinion, fancy,
   feel, form an opinion, gather, grant, guess, have a hunch,
   have an idea, have an impression, have an inkling, have the idea,
   hold, hold as, imagine, infer, judge, know, let, let be,
   look upon as, maintain, new, opine, pine, prefigure, presume,
   presuppose, presurmise, provisionally accept, reckon, regard,
   repute, say, sense, set down as, suppose, surmise, suspect,
   suspicion, take, take for, take for granted, take it, take to be,
   think, think of, trow, understand, view as, ween