One who speculates on abstruse or uncertain matters; one who devotes himself to speculation or theoretical reasoning.

A person versed in the theoretical aspects of something; a person devoted to a life of contemplation and study, spec. a member of a contemplative…

One who speculates, or indulges in abstract reasoning; a professed or habitual speculator; a theorist. (Very common from 1750.)

A speculator or speculatist. Obsolete. rare.

A speculative thinker; a theorist. Obsolete.

= speculatist, n.