The Collaborative International Dictionary of English v.0.48:

Streetwalker \Street"walk`er\, n.
   A common prostitute who walks the streets to find customers.
   [1913 Webster]

WordNet (r) 3.0 (2006):

streetwalker
    n 1: a prostitute who attracts customers by walking the streets
         [syn: streetwalker, street girl, hooker, hustler,
         floozy, floozie, slattern]