teaspoon vs teaspoonful

teaspoon

noun
  • A unit of measure, equivalent to one-third of a tablespoon or roughly five milliliters. 

  • A small spoon used to stir the contents of a cup or glass. 

verb
  • To serve with a teaspoon 

teaspoonful

noun
  • A unit of capacity equal to the amount a teaspoon can hold which is taken approximately as 5 ml. 

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