erstwhile vs later

erstwhile

adj

  • Former, previous. 

  • Respected, honourable. 

later

adj

  • At some time in the future. 

  • Coming afterward in distance (following an antecedent distance as embedded within an adverbial phrase) 

  • Coming afterward in time (used with than when comparing with another time). 

adv

  • Afterward in time (used with than when comparing with another time). 

  • At some unspecified time in the future. 

intj

  • See you later; goodbye. 

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