lexicologist

This term identifies a scholar focused on the theoretical and scientific analysis of a language's lexicon. It differs from a lexicographer, who is primarily concerned with the practical act of compiling and editing a dictionary. While the two roles often overlap, the lexicologist is more interested in the systemic patterns and evolutionary trajectories of words than in the production of a reference book.

Because it describes a professional specialization, the word carries a formal, academic connotation. It is typically used in linguistic discourse or institutional contexts to distinguish theoretical research from applied dictionary-making.