The study of the origin and historical development of words is called etymology. It examines how a word’s spelling, sound, structure, and meaning change over time.
Etymologists compare old written records, related languages, dialects, and patterns of sound change. When direct records are missing, they may reconstruct an earlier form by comparing cognates—related words inherited from a common ancestral language. English words can often be traced through Germanic, Latin, French, Greek, or other sources.
The word etymology comes from Ancient Greek etymologia, combining etymon, meaning “true sense,” with -logia, meaning “study” or “account.” The modern academic field developed alongside historical linguistics in the late 18th and 19th centuries.
A common mix-up is confusing etymology with entomology, the study of insects. Lexicography is different again: it focuses on compiling and editing dictionaries. Etymology can explain a word’s history, but that history does not necessarily determine the word’s modern meaning.