mouthing vs sounding

mouthing

noun
  • Ranting; passionate speech devoid of meaning. 

  • The act of forming a shape with the mouth, especially as part of sign language. 

sounding

noun
  • The action of the verb to sound. 

  • Any place or part of the ocean, or other water, where a sounding line will reach the bottom. 

  • The sand, shells, etc. brought up by the sounding lead when it has touched bottom. 

  • Test made with a probe or sonde. 

  • A measured depth of water. 

  • The act of inserting of a thin metal rod into the urethra of the penis for medical or sexual purposes 

adj
  • Emitting a sound. 

  • Sonorous. 

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