bite (n.) Look up bite at Dictionary.com
c. 1200, from bite (v.).
bite (v.) Look up bite at Dictionary.com
Old English bitan (class I strong verb; past tense bat, past participle biten), from Proto-Germanic *bitan (source also of Old Saxon bitan, Old Norse and Old Frisian bita, Middle Dutch biten, Dutch bijten, German beissen, Gothic beitan "to bite"), from PIE root *bheid- "to split," with derivatives in Germanic referring to biting.

To bite the bullet is said to be 1700s military slang, from old medical custom of having the patient bite a lead bullet during an operation to divert attention from pain and reduce screaming. Figurative use from 1891; the custom itself attested from 1840s. To bite (one's) tongue "refrain from speaking" is 1590s. To bite off more than one can chew (c. 1880) is U.S. slang, from plug tobacco.