The Collaborative International Dictionary of English v.0.48:

Hygienic \Hy`gi*en"ic\, a. [Cf. F. hygi['e]nique.]
   Of or pertaining to health or hygiene; sanitary.
   [1913 Webster]

WordNet (r) 3.0 (2006):

hygienic
    adj 1: tending to promote or preserve health; "hygienic habits
           like using disposable tissues"; "hygienic surroundings
           with plenty of fresh air" [syn: hygienic, hygienical]

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "hygienic":
   antiseptic, aseptic, beneficial, benign, boiled, bracing, clean,
   constitutional, decontaminated, disinfected, good, good for,
   health-enhancing, health-preserving, healthful, healthy, hygeian,
   invigorating, pasteurized, prophylactic, pure, refreshing,
   salubrious, salutary, sanitary, sterile, sterilized, tonic,
   uninfected, wholesome