dais vs rostrum

dais

noun
  • A raised platform in a room for a high table, a seat of honour, a throne, or other dignified occupancy, such as ancestral statues; a similar platform supporting a lectern, pulpit, etc., which may be used to speak from. 

  • The canopy over an altar, etc. 

  • A bench, a settle, a pew. 

rostrum

noun
  • A dais, pulpit, or similar platform for a speaker, conductor, or other performer. 

  • A platform for a film or television camera. 

  • The projecting prow of a rowed warship, such as a trireme. 

  • The beak-shaped projection on the head of insects such as weevils. 

  • The snout of a dolphin. 

  • The beak. 

  • The oral or nasal region of a human used for anatomical location (i.e. rostral) 

How often have the words dais and rostrum occurred in a corpus of books? (source: Google Ngram Viewer )