onrush vs sustenance

onrush

verb

  • To assault aggressively. 

  • To rush or flow forward forcefully. 

noun

  • An aggressive assault. 

  • A forceful rush or flow forward. 

sustenance

noun

  • Something that provides support or nourishment. 

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