antiknock

adjective

an·​ti·​knock ˌan-tē-ˈnäk 

ˌan-tī-

variants or anti-knock

: serving or intended to prevent detonation in the combustion process of an internal-combustion engine

an antiknock agent

an anti-knock fuel additive

Word History

First Known Use

1921, in the meaning defined above

Kids Definition

antiknock

noun

an·​ti·​knock

ˌant-i-ˈnäk,

ˌan-ˌtī-

: a substance that is added to the fuel of an internal combustion engine to help prevent knocking