Definitions:

1. a fundamental or central idea noun
   • Uncertainty is one of the keynotes of quantum theory.
2. the first note of a diatonic musical scale noun
   • C is the keynote of the scale.
3. the principal theme in a speech or literary work noun
   • Once I realized isolation was a keynote of the novel, all the symbolism made sense.
4. to deliver the keynote address to an audience verb
   • I'm supposed to keynote this conference.
5. to set the keynote of verb
   • That song keynotes the album.

Synonyms:

• tonic