keynote in WordNet English dictionary

1. a fundamental or central idea
   keynote 
   
2. (music) the first note of a diatonic scale
   tonic  keynote 
   
3. the principal theme in a speech or literary work
   keynote 
   

1. set the keynote of
   "Comfort keynotes this designer's Fall collection"
   keynote 
   
2. give the keynote address to (an audience)
   keynote