motormouth

• motor mouth, motor-mouth

motor +‎ mouth, from the figurative notion that the mouth talks so much that it seems motorized.

motormouth (plural motormouths)

1. (informal) One who talks very fast or incessantly; a chatty or loquacious person.

   Synonyms: see Thesaurus:chatterbox

   Coordinate terms: bigmouth, loudmouth

   He's such a motormouth that I can never get a word in.

   • 2014 October 11, Simon Hattenstone, “Russell Brand: ‘I want to address the alienation and despair’”, in The Guardian‎:

     Blimey, Brand is checking a word with me. This is nothing like the motor-mouth on the telly, laughing in the face of everything.

motormouth (third-person singular simple present motormouths, present participle motormouthing, simple past and past participle motormouthed)

1. (intransitive, informal) To talk very fast or incessantly.