tea spoonful vs teaspoon

tea spoonful

teaspoon

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

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

verb
  • To serve with a teaspoon 

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