This word is acceptable for play in the UK dictionary that is being used in the following games:

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n. One who speculates; a theorist.

n. One who speculates, or forms theories; a speculator; a theorist.

n. A speculative philosopher; a person who, absorbed with theoretical questions, pays little attention to practical conditions.

"There cannot, in nature, in theory, nor even in common sense, be a doubt of their equal right: but disquisitions on this point will remain rather curious than important, till the speculatist can superinduce to the abstract truth of the position some proof of its practicability."

speculator    theorist