A specialist in a given branch of knowledge:
The definition of a scientist is a person who is an expert in one of the natural or physical sciences.
someone who theorizes (especially in science or art)
Find another word for theorist. In this page you can discover 23 synonyms, antonyms, idiomatic expressions, and related words for theorist, like: philosopher, theorizer, theoretician, speculator, scholar, scientist, theoriser, idealogue, sociologist, thinker and realist.