Why is the ninth month called September?
c.1200, "observe, take mental note of, mark carefully," from Old French noter "indicate, designate; take note of, write down," from Latin notare "to mark, to note, to make a note," from nota "mark, sign, note, character, letter" (see note (n.)). Meaning "to set in writing" is from early 14c. Related: Noted; noting.
c.1300, "a song, music, instrumental music; a musical note," from Latin nota "letter, character, note," originally "a mark, sign, means of recognition," which is perhaps related to notus, past participle of noscere (Old Latin *gnoscere) "to know" (see know). Meaning "notice, attention, reputation" is early 14c. Meaning "brief writing" is from 1540s.
in the notation of Western music, sign indicating pitch by its position on the staff and showing duration by its shape. Notes evolved in the 13th century from neumes (q.v.), signs indicating relative or absolute pitch and nuance but not necessarily rhythm. The earliest notes were the longa, , and brevis, ; and their derivatives, the maxima, , and semibrevis, . In modern notation the brevis and semibrevis correspond to the double whole note, , and the whole note, . Other modern notes, in diminishing time value, are the half note, ; quarter note, ; eighth note, ; sixteenth note, ; thirty-second note, ; and sixty-fourth note, . Generally, music notation has favoured shorter note values in modern times.