even vs smoothen

even

verb
  • To make flat and level. 

noun
  • An even number. 

adj
  • Flat and level. 

  • Equal in proportion, quantity, size, etc. 

  • On equal monetary terms; neither owing nor being owed. 

  • parallel; on a level; reaching the same limit. 

  • On equal terms of a moral sort; quits. 

  • Convenient for rounding other numbers to; for example, ending in a zero. 

  • Without great variation. 

  • Divisible by two. 

adv
  • In reality; implying an extreme example in the case mentioned, as compared to the implied reality. 

  • Emphasizing a comparative. 

  • Signalling a correction of one's previous utterance; rather, that is. 

smoothen

verb
  • To make smooth. 

  • To become smooth. 

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