monotonic vs periodic

monotonic

adj
  • Uttered in a monotone; monotonous. 

  • said of a function that either never decreases or never increases as its independent variable increases. 

  • of or using the Greek system of diacritics which discards the breathings and employs a single accent to indicate stress. It replaced polytonic system in 1982. 

periodic

adj
  • Having a structure characterized by periodic sentences. 

  • Relating to the highest oxidation state of iodine; of or derived from a periodic acid. 

  • Periodical. 

  • Pertaining to the revolution of a celestial object in its orbit. 

  • Relative to a period or periods. 

  • Having repeated cycles. 

  • Occurring at regular intervals. 

  • For which any return to it must occur in multiples of k time steps, for some k>1. 

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