Having a tendency to reject the plans or proposals of others(adjective)
Such a person or organization(noun)
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Use "rejectionist" in a sentence
"First, and foremost, yes, the rejectionist is the new cool."
"Now - as a 'rejectionist' - how do YOU interpret it?"
"They say that no Palestinian who killed Israelis, no Palestinians belonging to the so-called rejectionist groups, Islamic Jihad, Hamas and the like, will be released in this first stage until peacemaking has gone much further down the road."