D defs.my
Entry 1 sense Webster, 1913

octane

/(ŏk"tān)/ · oc·tane · IPA /ˈɒkteɪn/
01 n. Any one of a group of metametric hydrocarbons (C8H18) of the methane (paraffin) series. The most important is a colorless, volatile, infla…
  1. 1.
    Any one of a group of metametric hydrocarbons (C8H18) of the methane (paraffin) series. The most important is a colorless, volatile, inflammable liquid, found in petroleum, and a constituent of gasoline or ligroin.(Chem.)