The Collaborative International Dictionary of English v.0.48:

Shoelace \Shoe"lace\, n.
   a length of cord for tying the upper parts of a shoe
   together. Commercial shoelaces usually come in different
   lengths, and have each end confined in a narrow plastic tube
   for convenience in inserting the cords through the holes in a
   shoe upper. Also called shoestring.
   [PJC]

WordNet (r) 3.0 (2006):

shoelace
    n 1: a lace used for fastening shoes [syn: shoelace, shoe
         lace, shoestring, shoe string]