The Collaborative International Dictionary of English v.0.48:

Sirocco \Si*roc"co\ (s[i^]*r[o^]k"k[-o]), n.; pl. Siroccos
   (s[i^]*r[o^]k"k[=o]z). [It. sirocco, scirocco, Ar. shorug,
   fr. sharq the rising of the sun, the east, fr, sharaca to
   rise as the sun. Cf. Saracen.]
   1. An oppressive, relaxing wind from the Libyan deserts,
      chiefly experienced in Italy, Malta, and Sicily.
      [1913 Webster]

   2. In general, any hot dry wind of cyclonic origin, blowing
      from arid or heated regions, including the desert wind of
      Southern California, the harmattan of the west coasts of
      Africa, the hot winds of Kansas and Texas, the kamsin of
      Egypt, the leste of the Madeira Islands, and the
      leveche of Spain.
      [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

sirocco
    n 1: a windstorm that lifts up clouds of dust or sand; "it was
         the kind of duster not experienced in years" [syn: dust
         storm, duster, sandstorm, sirocco]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "sirocco":
   Santa Ana, chinook, chinook wind, devil, dust storm, foehn,
   harmattan, hot wind, khamsin, peesash, samiel, sandstorm, shaitan,
   simoom, snow eater, solano, thawer, volcanic wind