Source : Webster's Revised Unabridged Dictionary (1913)

Hygiene \Hy"gi*ene\, n. [F. hygi[`e]ne. See {Hygeia}.]
   That department of sanitary science which treats of the
   preservation of health, esp. of households and communities; a
   system of principles or rules designated for the promotion of
   health.

Source : WordNet®

hygiene
     n 1: a condition promoting sanitary practices; "personal hygiene"
     2: the science concerned with the prevention of illness and
        maintenance of health [syn: {hygienics}]