Lexicography
Etymology
From Greek lexikon ("word-book") + graphein ("to write"), so literally "the writing of a wordbook." It shares its first half with "lexicon." Samuel Johnson, who compiled a landmark dictionary himself, famously defined the lexicographer as "a harmless drudge" — a wry acknowledgment of how patient the craft is.
noun · /lek-sih-KOG-ruh-fee/
The practice of compiling, writing, and editing dictionaries.
What it names
The painstaking work behind the reference we take for granted — the decisions about which words exist, what they mean, and how to say so.
Example
Modern lexicography waits for evidence, adding a slang word only once the citations pile up.
Related idea
Lexicography is the applied craft of making dictionaries; lexicology is the theoretical study of words and vocabulary. One ships a book; the other studies the phenomenon.