Definition of downtoner in English:

downtoner

Pronunciation /ˈdaʊntəʊnə/

noun

Grammar
  • An adverb or adverbial phrase that reduces the effect of the following adjective, adverb, noun, or verb (such as rather, fairly, sort of, etc.). Opposed to amplifier, intensifier.

Origin

Early 20th century. From down + tone + -er, after to tone down.