to force someone to clamp with their teeth, to force into someone's mouth (e.g. a gag) / to wedge into a space / to inflict (a blow), to deal (a hit)

(literally) To bite one's own navel / (idiomatic) To be deeply regretful about something

nail biting

to chew, to digest / to fully appreciate, to fully understand

Same as above.

(of pets, animals, etc...) play biting

(literally) for a dam to break and water to burst forth / (figuratively) to burst forth (e.g. tears, words, a crowd)

(idiomatic, chiefly Kansai, slang) to stare or glare in challenge; by extension, to pick a fight

Alternative form of メンチを切る

to be evident / to be obvious / to understand completely