blastoff vs point of departure

blastoff

noun
  • The countdown and launch of a rocket, missile or spacecraft 

point of departure

noun
  • Synonym of starting point 

  • of abstract processes that can be compared to a voyage: initial circumstances. Frequent collocations include, but are not limited to 

  • a dosage level at which additional administration of an agent significantly loses its efficacy 

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