keynote

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

How keynote is being used?