hydrous vs seawater

hydrous

adj
  • Containing combined water; hydrated. 

seawater

adj
  • Consisting of seawater. 

  • Associated in some way with seawater, or intended for dealing with seawater. 

noun
  • The saltwater of a sea or ocean. 

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