The Collaborative International Dictionary of English v.0.48:

Isopoda \I*sop"o*da\, n. pl. [NL. See Iso-, and -poda.]
   (Zool.)
   An order of sessile-eyed Crustacea, usually having seven
   pairs of legs, which are all similar in structure.
   [1913 Webster]

   Note: The body is usually depressed, with the abdominal
         segments short, and often consolidated in part. The
         branchi[ae] are on the abdominal appendages. The group
         includes the terrestrial pill bugs and sow bugs, with
         numerous marine forms. See Arthrostrata, Gribble.
         [1913 Webster]

WordNet (r) 3.0 (2006):

Isopoda
    n 1: woodlice [syn: Isopoda, order Isopoda]