aliphatic

a. [ Gr. &unr_;, &unr_;, oil, fat. ] (Org. Chem.) Of, pertaining to, or derived from, fat; fatty; -- applied to compounds having an open-chain structure. The aliphatic compounds thus include not only the fatty acids and other derivatives of the paraffin hydrocarbons, but also unsaturated compounds, as the ethylene and acetylene series. Compare alicyclic and aromatic. [ Webster 1913 Suppl. ]