The Collaborative International Dictionary of English v.0.48:

Harvestman \Har"vest*man\ (-man), n.; pl. Harvestmen (-men).
   1. A man engaged in harvesting. --Shak.
      [1913 Webster]

   2. (Zool.) See Daddy longlegs, 1.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Phalangoidea \Phal`an*goi"de*a\, n. pl. [NL., from Phalangium
   the daddy longlegs (see Phalangious) + Gr. e'i^dos form.]
   (Zool.)
   A division of Arachnoidea, including the daddy longlegs or
   harvestman (Phalangium) and many similar kinds. They have
   long, slender, many-jointed legs; usually a rounded,
   segmented abdomen; and chelate jaws. They breathe by
   trache[ae]. Called also Phalangides, Phalangidea,
   Phalangiida, and Opilionea.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Daddy longlegs \Dad"dy long"legs`\
   1. (Zool.) An arachnidan of the genus Phalangium, and
      allied genera, having a small body and four pairs of long
      legs; -- called also harvestman, carter, and
      grandfather longlegs.
      [1913 Webster]

   2. (Zool.) A name applied to many species of dipterous
      insects of the genus Tipula, and allied genera, with
      slender bodies, and very long, slender legs; the crane
      fly; -- called also father longlegs.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Carter \Cart"er\, n.
   1. A charioteer. [Obs.] --Chaucer.
      [1913 Webster]

   2. A man who drives a cart; a teamster.
      [1913 Webster]

   3. (Zool.)
      (a) Any species of Phalangium; -- also called
          harvestman.
      (b) A British fish; the whiff.
          [1913 Webster]

WordNet (r) 3.0 (2006):

harvestman
    n 1: spiderlike arachnid with a small rounded body and very long
         thin legs [syn: harvestman, daddy longlegs, Phalangium
         opilio]