Lexicology
Etymology
From Greek "lexikon" (of or for words), from "lexis" (word, speech), plus "-logia" (study of). It is the scholarly counterpart to "lexicography," the practical craft of actually compiling dictionaries.
noun · /lek-sih-KOL-uh-jee/
The branch of linguistics that studies words — their meanings, forms, history, and relationships.
What it names
The systematic study of vocabulary itself, the theory behind every dictionary.
Example
Her thesis in lexicology traced how a single slang word acquired five new meanings in a decade.
Related idea
Lexicology is the study of words as a system; lexicography is the applied art of writing them up into a dictionary.