characteristic vs especial

characteristic

adj
  • Being a distinguishing feature of a person or thing. 

noun
  • A distinguishing feature of a person or thing. 

  • For a given field or ring, a natural number that is either the smallest positive number n such that n instances of the multiplicative identity (1) summed together yield the additive identity (0) or, if no such number exists, the number 0. 

  • The integer part of a logarithm. 

  • The distinguishing features of a navigational light on a lighthouse etc by which it can be identified (colour, pattern of flashes etc.). 

especial

adj
  • Exceptional in importance or significance; special. 

  • Particular. 

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