Source : Webster's Revised Unabridged Dictionary (1913)

Aliphatic \Al`i*phat"ic\, a. [Gr. ?, ?, oil, fat.] (Org. Chem.)
   Of, pertaining to, or derived from, fat; fatty; -- applied to
   compounds having an openc-hain 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.

Source : WordNet®

aliphatic
     adj : having carbon atoms linked in open chains