Etymology of "Swell": Four Distinct Origins for Four Meanings

The word swell has separate etymological roots for each major sense:

1. Adjective: "excellent, stylish" (late 18th c.) – British slang; possibly from swingeing ("large, impressive") or influenced by swill.
2. Verb: "enlarge, inflate" (early 16th c.) – Middle English swellen from Old English swellan; cognate with Old Norse svella.
3. Noun: "large ocean wave" (mid-19th c.) – Surfers' slang; shortening of swellhead (wave with pronounced bulge).
4. Exclamation: "great!" (late 19th c.) – Possibly clipped from "swell thing"; popularized in early 20th-c. US.

A single form, four independent histories.