keynote Definition

1. The note on which a musical scale or key is based; the tonic.
2. A central theme, principle or controlling thought.

Thesaurus: standard, basic idea, stress, motif, theme, marrow, kernel, heart, essence, gist, core, emphasis, accent.
3a. Said of a speech, etc: expounding central principles;
3b. Said of a speech, etc: setting the tone for a meeting, etc.
4. Of fundamental importance.

1. To deliver a keynote speech.
2. To give the keynote.