Webster's 1828 Dictionary
SYNONYMIZE
v.t.To express the same meaning in different words.
Webster's 1913 Dictionary
SYNONYMIZE
Syn *on "y *mize, v. t. [imp. & p. p. Synonymized; p. pr. & vb. n.Synonymizing.]
Defn: To express by a synonym or synonyms; to give the synonym or synonyms corresponding to. This word "fortis " we may synonymize after all these fashions: stout, hardy, valiant, doughty, courageous, adventurous, brave, bold, daring, intrepid. Camden.
The Wordsmith Dictionary