bonus

Bonus (BOH-nuss, "good") is the ordinary Latin adjective for good, and the record shows it living everywhere at once: 12,785 occurrences across 349 works, one of the densest and most widely spread words in the corpus. Its heaviest homes are the moral and rhetorical prose. Seneca's Ad Lucilium Epistulae Morales ("Moral Letters to Lucilius") leads with 998, then Quintilian's Institutio Oratoria ("The Training of the Orator," 498), Cicero's de Finibus Bonorum et Malorum ("On the Ends of Goods and Evils," 464), Livy's Ab Urbe Condita ("From the Founding of the City," 411), Pliny's Naturalis Historia ("Natural History," 389), and Tertullian's Adversus Marcionem ("Against Marcion," 308). The word is at home wherever Romans weighed what is good — in ethics, oratory, history, and theology alike.

The lexica are unanimous on the sense and reach past it to an older shape. Lewis & Short (A Latin Dictionary, 1879) glosses bonus simply as "good" and records the archaic form duonus ("good") from the Carmen Saliare ("Salian hymn"). de Vaan (Etymological Dictionary of Latin, Brill 2008) also glosses "good," and preserves the oldest witnesses: duenas, duenoi ("good") on the Duenos inscription (CIL 1.4), duonus in the Carmen Saliare. He files the derivatives bene ("well") and bellus ("pretty, fine") under the same root — the pretty word and the moral one share one ancestor. Walde–Hofmann (Lateinisches etymologisches Wörterbuch, 1938–54) gives the same old forms dvonos and dvenos.

On the etymology the record carries three matched pointers: de Vaan proposes the root candidates *dweno-, *due-, *duo-; Walde–Hofmann offers *dou- and *deu-; and Ernout–Meillet (Dictionnaire étymologique de la langue latine, DELL, 1932; 4th ed. 1959) treats the word as well. The citable surfaces are all Livy's, and they run mostly through the comparatives — melior ("better"), optimus ("best"), melius ("better," adverb) — the word caught in the act of measuring one good against another (Livy, Ab Urbe Condita 1, p15, p19, p20).

If "good" and "pretty" grew from one root, when did the Romans decide they were two words?