grow vs slacken

grow

verb
  • To appear or sprout. 

  • To become larger, to increase in magnitude. 

  • To undergo growth; to be present (somewhere) 

  • To develop, to mature. 

  • To cause or allow something to become bigger, especially to cultivate plants. 

  • To assume a condition or quality over time. 

slacken

verb
  • To make slack, less taut, or less intense. 

  • To gradually decrease in intensity or tautness; to become slack. 

  • To deprive of cohesion by combining chemically with water; to slake. 

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