The Collaborative International Dictionary of English v.0.48:

dactyl \dac"tyl\ (d[a^]k"t[i^]l), n. [L. dactylus, Gr. da`ktylos
   a finger, a dactyl. Cf. Digit.]
   1. (Pros.) A poetical foot of three sylables (--- [crescent]
      [crescent]), one long followed by two short, or one
      accented followed by two unaccented; as, L.
      t["e]gm[i^]n[e^], E. mer[bprime]ciful; -- so called from
      the similarity of its arrangement to that of the joints of
      a finger. [Written also dactyle.]
      [1913 Webster]

   2. (Zool.)
      (a) A finger or toe; a digit.
      (b) The claw or terminal joint of a leg of an insect or
          crustacean.
          [1913 Webster]

WordNet (r) 3.0 (2006):

dactyl
    n 1: a metrical unit with stressed-unstressed-unstressed
         syllables
    2: a finger or toe in human beings or corresponding body part in
       other vertebrates [syn: digit, dactyl]

Moby Thesaurus II by Grady Ward, 1.0:

77 Moby Thesaurus words for "dactyl":
   Alexandrine, accent, accentuation, amphibrach, amphimacer,
   anacrusis, anapest, antispast, arsis, bacchius, beat, cadence,
   caesura, catalexis, chloriamb, chloriambus, colon, counterpoint,
   cretic, dactylic hexameter, diaeresis, dimeter, dipody, dochmiac,
   elegiac, elegiac couplet, elegiac pentameter, emphasis, epitrite,
   feminine caesura, foot, heptameter, heptapody, heroic couplet,
   hexameter, hexapody, iamb, iambic, iambic pentameter, ictus, ionic,
   jingle, lilt, masculine caesura, measure, meter, metrical accent,
   metrical foot, metrical group, metrical unit, metron, molossus,
   mora, movement, numbers, paeon, pentameter, pentapody, period,
   proceleusmatic, pyrrhic, quantity, rhythm, spondee, sprung rhythm,
   stress, swing, syzygy, tetrameter, tetrapody, tetraseme, thesis,
   tribrach, trimeter, tripody, triseme, trochee