anti-knockadj.n.
/ˌantɪˈnɒk/, U.S. /ˌæn(t)iˈnɑk/, /ˌænˌtaɪˈnɑk/, /ˌæn(t)əˈnɑk/ A. adj.
Designating a fuel, fuel additive, piece of technology, etc., in an internal combustion engine, designed to reduce or prevent premature combustion (see knock n.1 1c). Also: of or relating to such reduction or prevention of engine knock.
ΚΠ
1921 Flight 16 June 412/2 Benzole and similar anti-knock fuels are, however, permitted.
1937 Life 10 May (verso front cover) (advt.) More anti-knock fluid (containing lead tetraethyl) at pumps marked ‘Ethyl’ than you get in the best regular-grade gasoline.
1989 Green Mag. Dec. 73/1 Lead gets its anti-knock effect by slowing combustion, leading to higher levels of unburned hydrocarbon emissions.
2019 mirror.co.uk (Nexis) 5 Jan. Rather remarkably, the fuel consumption is down by 4%, and anti-knock tech hidden in there somewhere means you can almost run it on used cooking oil.
B. n.
A substance added to an internal combustion engine's fuel, designed to reduce or prevent premature combustion.
ΚΠ
1925 Proc. Conf. Tetraethyl Lead Gasoline (U.S. Public Health Bull. No. 158) 8 We tried one of the selenium metallo-organic compounds. We found that was an antiknock.
2013 News Jrnl. (Wilmington, Delaware) 5 June The manufacture of tetrathyl lead antiknocks.
This entry has been updated (OED Third Edition, March 2022).
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adj.n.1921