Source : Webster's Revised Unabridged Dictionary (1913)

Aldol \Al"dol\, n. [Aldehyde + -ol as in alcohol.] (Chem.)
   A colorless liquid, {C4H8O2}, obtained by condensation of two
   molecules of acetaldehyde: CH3CHO + CH3CHO = H3CH(OH)CH2CO;
   also, any of various derivatives of this. The same reaction
   has been applied, under the name of

   {aldol condensation}, to the production of many compounds.