The Collaborative International Dictionary of English v.0.48:

Absent \Ab"sent\, a. [F., fr. absens, absentis, p. pr. of abesse
   to be away from; ab + esse to be. Cf. Sooth.]
   1. Being away from a place; withdrawn from a place; not
      present. "Expecting absent friends." --Shak.
      [1913 Webster]

   2. Not existing; lacking; as, the part was rudimental or
      absent.
      [1913 Webster]

   3. Inattentive to what is passing; absent-minded;
      preoccupied; as, an absent air.
      [1913 Webster]

            What is commonly called an absent man is commonly
            either a very weak or a very affected man.
                                                  --Chesterfield.
      [1913 Webster]

   Syn: Absent, Abstracted.

   Usage: These words both imply a lack of attention to
          surrounding objects. We speak of a man as absent when
          his thoughts wander unconsciously from present scenes
          or topics of discourse; we speak of him as abstracted
          when his mind (usually for a brief period) is drawn
          off from present things by some weighty matter for
          reflection. Absence of mind is usually the result of
          loose habits of thought; abstraction commonly arises
          either from engrossing interests and cares, or from
          unfortunate habits of association.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Absent \Ab*sent"\, v. t. [imp. & p. p. Absented; p. pr. & vb.
   n. Absenting.] [Cf. F. absenter.]
   1. To take or withdraw (one's self) to such a distance as to
      prevent intercourse; -- used with the reflexive pronoun.
      [1913 Webster]

            If after due summons any member absents himself, he
            is to be fined.                       --Addison.
      [1913 Webster]

   2. To withhold from being present. [Obs.] "Go; for thy stay,
      not free, absents thee more." --Milton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

absent
    adj 1: not being in a specified place [ant: present]
    2: nonexistent; "the thumb is absent"; "her appetite was
       lacking" [syn: lacking, absent, missing, wanting]
    3: lost in thought; showing preoccupation; "an absent stare";
       "an absentminded professor"; "the scatty glancing quality of
       a hyperactive but unfocused intelligence" [syn: absent,
       absentminded, abstracted, scatty]
    v 1: go away or leave; "He absented himself" [syn: absent,
         remove]

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "absent":
   absconded, absentminded, absorbed, abstracted, away, bemused,
   castle-building, daydreaming, daydreamy, deficient, deleted,
   departed, disappeared, distrait, dreaming, dreamy, drowsing,
   ecstatic, elsewhere, engrossed, faraway, forgetful, gone,
   half-awake, heedless, in a reverie, in the clouds, keep away from,
   lacking, lost, lost in thought, meditative, missing, mooning,
   moonraking, museful, musing, napping, no longer present, nodding,
   nonattendant, nonexistent, not found, not present, oblivious, off,
   omitted, out, out of sight, pensive, pipe-dreaming, preoccupied,
   rapt, somewhere else, stargazing, subtracted, taken away, taken up,
   transported, unconscious, vanished, wanting, withdraw from,
   woolgathering, wrapped in thought



The Devil's Dictionary (1881-1906):

ABSENT, adj.  Peculiarly exposed to the tooth of detraction; vilifed;
hopelessly in the wrong; superseded in the consideration and affection
of another.

    To men a man is but a mind.  Who cares
    What face he carries or what form he wears?
    But woman's body is the woman.  O,
    Stay thou, my sweetheart, and do never go,
    But heed the warning words the sage hath said:
    A woman absent is a woman dead.
                                                            Jogo Tyree