antiknock

[ an-tee-nok, an-tahy-, an-tee-nok, an-tahy- ]
/ ˌæn tiˈnɒk, ˌæn taɪ-, ˈæn tiˌnɒk, ˈæn taɪ- /

adjective

noting or pertaining to a substance, as tetraethyllead or ferrocene, used as a fuel additive for an internal-combustion engine to eliminate or minimize knock.

noun

such a substance added to fuel in an internal-combustion engine.

Origin of antiknock

First recorded in 1920–25; anti- + knock
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for antiknock

antiknock
/ (ˌæntɪˈnɒk) /

noun

a compound, such as lead tetraethyl, added to petrol to reduce knocking in the engine
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012