bass (adj.)youdaoicibaDictYouDict[bass 词源字典]
late 14c., of things, "low, not high," from Late Latin bassus "short, low" (see base (adj.)). Meaning "low in social scale or rank" is recorded from late 14c. Of voices and music notes, from mid-15c. (technically, ranging from the E flat below the bass stave to the F above it), infuenced by Italian basso. Meaning "lowest part of a harmonized musical composition" is from mid-15c. Meaning "bass-viol" is from 1702; that of "double-bass" is from 1927.[bass etymology, bass origin, 英语词源]
harmonize (v.)youdaoicibaDictYouDict
late 15c., "play or sing in harmony," from French harmoniser (15c.), from Old French harmonie (see harmony). Meaning "be in harmony (with), go well together" is from 1620s. Transitive sense "bring into harmony" is from 1700; figurative sense "bring into agreement" is from 1767. Meaning "add harmony to (a melody)" is from 1790. Related: Harmonized; harmonizing.