—n. 1. Music.the note or tone on which a key or system of tones is founded; the tonic.
2. the main idea or central principle of a speech, program, thought, action, etc.
3. the policy line to be followed, as by a party in a political campaign, that is set forth authoritatively in advance by an address or other formal announcement.
4. See keynote address.
—v.t. 1. to announce the policy of (a political party, campaign, assembly, etc.); deliver a keynote address at: The governor will keynote the convention. 2. to serve as the keynote for.
3. Music.to give the keynote of.
—v.i. to provide a keynote, esp. a keynote address: He refused an invitation to keynote.