The curb put into the mouths of horses to restrain them. The Hebrew word (metheg) so rendered in Ps. 32:9 is elsewhere translated “bridle” (2 Kings 19:28; Prov. 26:3; Isa. 37:29). Bits were generally made of bronze or iron, but sometimes also of gold or silver. In James 3:3 the Authorized Version translates the Greek word by “bits,” but the Revised Version by “bridles.”
Bit
2 verses
Psalms
Psalms 32:9
Be ye not as the horse, or as the mule, which have no understanding: whose mouth must be held in with bit and bridle, lest they come near unto thee.
James
James 3:3
Behold, we put bits in the horses' mouths, that they may obey us; and we turn about their whole body.
From Easton's Bible Dictionary
Matthew George Easton, 1897