The Collaborative International Dictionary of English v.0.48:

Tent \Tent\, n. [OE. tente, F. tente, LL. tenta, fr. L. tendere,
   tentum, to stretch. See Tend to move, and cf. Tent a roll
   of lint.]
   1. A pavilion or portable lodge consisting of skins, canvas,
      or some strong cloth, stretched and sustained by poles, --
      used for sheltering persons from the weather, especially
      soldiers in camp.
      [1913 Webster]

            Within his tent, large as is a barn.  --Chaucer.
      [1913 Webster]

   2. (Her.) The representation of a tent used as a bearing.
      [1913 Webster]

   Tent bed, a high-post bedstead curtained with a tentlike
      canopy.

   Tent caterpillar (Zool.), any one of several species of
      gregarious caterpillars which construct on trees large
      silken webs into which they retreat when at rest. Some of
      the species are very destructive to fruit trees. The most
      common American species is the larva of a bombycid moth
      (Clisiocampa Americana). Called also lackery
      caterpillar, and webworm.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Webworm \Web"worm`\, n. (Zool.)
   Any one of various species of moths whose gregarious larvae
   eat the leaves of trees, and construct a large web to which
   they retreat when not feeding.
   [1913 Webster]

   Note: The most destructive webworms belong to the family
         Bombycidae, as the fall webworm (Hyphantria
         textor), which feeds on various fruit and forest
         trees, and the common tent caterpillar, which feeds on
         various fruit trees (see Tent caterpillar, under
         Tent.) The grapevine webworm is the larva of a
         geometrid moth (see Vine inchworm, under Vine).
         [1913 Webster]

WordNet (r) 3.0 (2006):

webworm
    n 1: several gregarious moth larvae that spin webs over foliage
         on which they feed