cannon bit
noun1
A smooth round bit for a horse.
- I’ll be bound, Lady Ashton understands every machine for breaking in the human mind, and there are as many as there are cannon-bit, martingales, and cavessons for young colts.1819, Jedediah Cleishbotham [pseudonym; Walter Scott], Tales of My Landlord, Third Series. […], volume III (The Bride of Lammermoor), Edinburgh: […] [James Ballantyne and Co.] for Archibald Constable and Co.; London: Longman, Hurst, Rees, Orme, and Brown, […]; Hurst, Robinson, and Co. […], →OCLC, page 8: