Entry 1 sense Webster, 1913 Speculatist /(spĕk"ū̇*lȧ*tĭst)/ · Spec·u·la·tist · IPA 01 n. One who speculates, or forms theories; a speculator; a theorist. 1. One who speculates, or forms theories; a speculator; a theorist. “The very ingenious speculatist, Mr. Hume.” — V. Knox.