ligationPronunciation: /lɪˈgeɪʃ(ə)n/Definition of ligation noun [mass noun] 1the surgical procedure of tying a ligature tightly around a blood vessel or other duct or tube in the body: the ligation of the cystic duct 2 Biochemistry the joining of two DNA strands or other molecules by a phosphate ester linkage. Origin: late Middle English: from late Latin ligatio(n-), from the verb ligare (see ligate)ligation in other Oxford dictionaries Definition of ligation in the US English dictionary