Webster's Revised Unabridged Dictionary · 1913

Heptane

Heptane , noun

[Greek "epta` seven.]

(Chemistry) Any one of several isometric hydrocarbons, C7H16, of the paraffin series (nine are possible, four are known); -- so called because the molecule has seven carbon atoms. Specifically, a colorless liquid, found as a constituent of petroleum, in the tar oil of cannel coal, etc.