The Collaborative International Dictionary of English v.0.48:

Syphilis \Syph"i*lis\, n. [NL., fr. Syphilus, the name of a
   shepherd in the Latin poem of Fracastoro, "Syphilus, sive
   Morbus Gallicus," which was published in 1530; Gr. ? hog,
   swine + ? dear, loving. The term was introduced into nosology
   by Sauvages.] (Med.)
   The pox, or venereal disease; a chronic, specific, infectious
   disease, usually communicated by sexual intercourse or by
   hereditary transmission, and occurring in three stages known
   as primary, secondary, and tertiary syphilis. See under
   Primary, Secondary, and Tertiary.
   [1913 Webster]

WordNet (r) 3.0 (2006):

syphilis
    n 1: a common venereal disease caused by the treponema pallidum
         spirochete; symptoms change through progressive stages; can
         be congenital (transmitted through the placenta) [syn:
         syphilis, syph, pox, lues venerea, lues]