The Collaborative International Dictionary of English v.0.48:

Vermicelli \Ver`mi*cel"li\, n. [It., pl. of vermicello,
   literally, a little worm, dim. of verme a worm, L. vermis.
   See Worm, and cf. Vermicule, Vermeil.]
   The flour of a hard and small-grained wheat made into dough,
   and forced through small cylinders or pipes till it takes a
   slender, wormlike form, whence the Italian name. When the
   paste is made in larger tubes, it is called macaroni.
   [1913 Webster]

WordNet (r) 3.0 (2006):

vermicelli
    n 1: pasta in strings thinner than spaghetti