Source : Webster's Revised Unabridged Dictionary (1913)

Olfaction \Ol*fac"tion\, n. [See {Olfactory}.] (Physiol.)
   The sense by which the impressions made on the olfactory
   organs by the odorous particles in the atmosphere are
   perceived.

Source : WordNet®

olfaction
     n : the faculty of smell [syn: {smell}, {sense of smell}, {olfactory
         modality}]