The Collaborative International Dictionary of English v.0.48:

Loiter \Loi"ter\, v. i. [imp. & p. p. Loitered; p. pr. & vb.
   n. Loitering.] [D. leuteren to delay, loiter; cf; Prov. G.
   lottern to be louse, lotter louse, slack, unsettled, vagrant,
   OHG. lotar.]
   1. To be slow in moving; to delay; to linger; to be dilatory;
      to spend time idly; to saunter; to lag behind.
      [1913 Webster]

            Sir John, you loiter here too long.   --Shak.
      [1913 Webster]

            If we have loitered, let us quicken our pace.
                                                  --Rogers.
      [1913 Webster]

   2. To wander as an idle vagrant. [Obs.] --Spenser.

   Syn: To linger; delay; lag; saunter; tarry.
        [1913 Webster]

WordNet (r) 3.0 (2006):

loiter
    v 1: be about; "The high school students like to loiter in the
         Central Square"; "Who is this man that is hanging around
         the department?" [syn: loiter, lounge, footle,
         lollygag, loaf, lallygag, hang around, mess
         about, tarry, linger, lurk, mill about, mill
         around]

Moby Thesaurus II by Grady Ward, 1.0:

98 Moby Thesaurus words for "loiter":
   abide, await, bide, bide the issue, bum, bum around, coquet,
   dabble, dally, dawdle, delay, diddle, dillydally, do nothing,
   doodle, drag, fall behind, falter, fiddle, fiddle with,
   fiddle-faddle, fidget with, finger with, flag, flirt, fool,
   fool around, fool with, fribble, frivol, get behind, goof off,
   halt, hang about, hang around, hang back, hold everything, hold on,
   hold your horses, horse around, idle, jerk off, kid around, lag,
   laze, lazy, lie around, linger, linger behind, loaf, loiter about,
   loll, loll around, lollop around, lollygag, lounge, lounge around,
   mark time, mess around, monkey, monkey around, mooch around, moon,
   moon around, piddle, play, play around, play with, poke, potter,
   procrastinate, put off, putter, shilly-shally, sit around,
   sit tight, sit up, slouch, slouch around, smatter, stand around,
   stay, stay up, stick around, straggle, take time, tarry, tinker,
   toy, toy with, trail, trail behind, trifle, twiddle, wait,
   wait a minute, wait and see, waste time