The Collaborative International Dictionary
Desynonymize
Desynonymize \De`syn*on"y*mize\, v. t.
To deprive of synonymous character; to discriminate in use;
-- applied to words which have been employed as synonyms.
--Coleridge. Trench.
Wiktionary
desynonymize
vb. To deprive of synonymous character; to cause no longer to be synonyms.