The Collaborative International Dictionary
Disagreer
Disagreer \Dis`a*gre"er\ (d[i^]s`[.a]*gr[=e]"[~e]r), n.
One who disagrees.
--Hammond.
Wiktionary
disagreer
n. One who disagrees.
Usage examples of "disagreer".
From religious contrasts arise the thought-categories of believer and non-believer, from economics those of co-worker and competitor, from ideological those of agreer and disagreer.