lettuce vs vegetable

lettuce

noun
  • An edible plant, Lactuca sativa and its close relatives, having a head of green and/or purple leaves. 

  • long hair, as worn by an exemplar of bro culture 

  • The leaves of the lettuce plant, eaten as a vegetable; as a dish often mixed with other ingredients, dressing etc. 

  • United States paper currency; dollars. 

  • A strong yellow-green colour, like that of lettuce (also called lettuce green). 

  • weed or marijuana 

vegetable

noun
  • The edible part of such a plant. 

  • A person whose brain (or, infrequently, body) has been damaged so that they cannot interact with the surrounding environment; a person in a persistent vegetative state. 

  • Any plant. 

  • A plant raised for some edible part of it, such as the leaves, roots, fruit or flowers, but excluding any plant considered to be a fruit, grain, herb, or spice in the culinary sense. 

adj
  • Of or relating to plants. 

  • Of or relating to vegetables. 

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