A person who makes conjectures; someone who guesses or forms opinions based on incomplete evidence.
From conjecture plus -er suffix (meaning 'one who does'). The -er suffix is one of English's oldest and most productive agent-noun markers, used since Old English times.
A conjecturer is essentially an intellectual risk-taker—throughout history, the people brave enough to conjecture have often been those who changed how we understand the world.
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