The Collaborative International Dictionary of English v.0.48:

Symphyla \Sym*phy"la\, n. pl. [NL., fr. Gr. sy`n with + ? a
   clan.] (Zool.)
   An order of small apterous insects having an elongated body,
   with three pairs of thoracic and about nine pairs of
   abdominal legs. They are, in many respects, intermediate
   between myriapods and true insects.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Symphyla
    n 1: small class of minute arthropods; unimportant except for
         the garden centipede [syn: Symphyla, class Symphyla]