Of a person, his or her mind, etc.: given to forming or developing theories; speculative. Obsolete.

Of a person: given to or concerned with forming or developing theories; speculative; influenced by theory.

Of a person: given to or concerned with forming or developing theories; speculative; influenced by theory. Sometimes opposed to practical. Now rare.

Characterized or distinguished by strong views as opposed to social position. Obsolete. rare.

Of a person: concerned with theoretical matters and speculation as opposed to practical matters and practice. Cf. theoretical, adj. 2b. Now rare.

Of a person: that engages in or tends towards theoretical, rather than practical thinking. Obsolete.

That theorizes; having a propensity to theorize. Frequently in negative contexts.