'Thinner' definitions:

Definition of 'thinner'

From: WordNet
noun
A diluting agent [syn: dilutant, diluent, thinner]

Definition of 'Thinner'

From: GCIDE
  • Thinner \Thin"ner\, n. One who thins, or makes thinner. [1913 Webster] [1913 Webster]

Synonyms of 'thinner'

From: Moby Thesaurus