What is "octyl"

Octyl \Oc"tyl\, n. [Octane + -yl.] (Chem.) A hypothetical hydrocarbon radical regarded as an essential residue of octane, and as entering into its derivatives; as, octyl alcohol.

n. (context organic chemistry English) Any of very many isomeric univalent hydrocarbon radicals, C₈H₁₇, formally derived from octane by the loss of a hydrogen atom