I often use the word swell as an adverb meaning "excellent". That comes from a now-archaic adjective meaning "stylish" which was first attested in 1810 (use of it as a single positive expression is from 1930s American slang). That in turn is from a noun meaning "stylish person", which comes from the verb for "enlarge" because stylish people were thought to have swollen egos. Through Middle English swellen and Old English swellan, the verb traces to the Proto-Germanic word swellana, which is thought to derive from an unknown Proto-Indo-European root. Use of swell in a figurative manner (such as to swell with pride or swell with anger) began in the late 1300s, and usage of the word swell over time has been decreasing since a swell in the eighteenth century.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.