lip vs oral cavity

lip

noun
  • Either of the two fleshy protrusions around the opening of the mouth. 

  • Backtalk; verbal impertinence. 

  • One of the two opposite divisions of a labiate corolla. 

  • The sharp cutting edge on the end of an auger. 

  • A part of the body that resembles a lip, such as the edge of a wound or the labia. 

  • The projecting rim of an open container; a short open spout. 

  • One of the edges of the aperture of a univalve shell. 

  • The edge of a high spot of land. 

  • The distinctive petal of the Orchis family. 

  • Embouchure: the condition or strength of a wind instrumentalist's lips. 

verb
  • To change the sound of (a musical note played on a wind instrument) by moving or tensing the lips. 

  • To form the rim, edge or margin of something. 

  • To simulate speech by moving the lips without making any sound; to mouth. 

  • (of something inanimate) To touch lightly. 

  • To touch or grasp with the lips; to kiss; to lap the lips against (something). 

  • To make a golf ball hit the lip of the cup, without dropping in. 

  • To utter verbally. 

  • To rise or flow up to or over the edge of something. 

  • To wash against a surface, lap. 

oral cavity

noun
  • The cavity of the mouth, especially the part of the mouth behind the gums and teeth that is bounded above by the hard and soft palates and below by the tongue and by the mucous membrane connecting it with the inner part of the mandible. 

  • The hollow on the lower surface of the head from which the proboscis protrudes. 

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