- keynote (n.)
[keynote 词源字典]
- also key-note, "lowest note of a musical scale, basis of a scale," 1776, from key (n.1) in sense of "musical scale" + note (n.). Figurative sense of "leading idea" is from 1783; keynote address is 1905, American English.[keynote etymology, keynote origin, 英语词源]