/ ˈkiːnəʊt; NAmE -noʊt/ noun
1.
[ usually sing. ] the central idea of a book, a speech, etc. :
Choice is the keynote of the new education policy.
a keynote speech / speaker (= a very important one, introducing a meeting or its subject)
2.
( music ) the note on which the key is based
► key·noter noun :
For the first time, a woman will be the keynoter at the convention this year.