bathroom vs necessarium

bathroom

noun
  • A lavatory: a room containing a toilet and (typically but not necessarily) a bathtub. 

  • A room containing a shower and/or bathtub, and (typically but not necessarily) a toilet. 

verb
  • To assist a patient with using the toilet and general personal hygiene. 

necessarium

noun
  • A lavatory. 

  • Synonym of reredorter: a monastery's latrine, outhouse, or lavatory, typically located behind the dormitory. 

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