smell-o-vision

Short definition from Wiktionary

Noun

1. 1
   A (supposed) technology consisting of cinematography with the addition of olfaction, often portrayed as far-fetched or futuristic.
2. 2
   Alternative letter-case form of smell-o-vision.

Proper noun

1. 1
   Alternative letter-case form of Smell-O-Vision.
2. 2
   A system that choreographed the release of odors into a movie theater during the projection of a film.