One fond of his own notions, or unduly attached to his own opinions.(noun)
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Use "opinionist" in a sentence
"Speaking of wealthy welfare, I heard a news "opinionist" ask if there weren't some weathy people out there who would pitch in to save the AIG since they were the beneficiaries of the current crisis ... no-one ponied up."
"Organised by Metro magazine, the Metro Mayoral Super Quiz is under the adjudication of renowned 'opinionist' Te Radar."
"Its not likely to happen, it will put too many 'opinionist's' out of work."