hoop; metal band
A metal or bamboo hoop used to bind the staves of a barrel, bucket, or similar container. Also used in figurative expressions about restraint.
The hoop on the old bucket came off.
discipline; self-control; solidarity
Figurative use, often in set phrases like 箍が外れる (to lose self-control) or 箍を締める (to tighten discipline). Describes the mental or social 'hoop' that keeps behavior in check.
I tightened the hoop and repaired the bucket.
When I drink, my self-control slips and I don't know what I might say.
To tighten the team's discipline, we started rigorous training.
Katakana spelling is sometimes used for emphasis or in informal writing.
Kana spelling is common, especially for the figurative sense. It is usually written in kana.
Rarely used kanji form.
The native word たが denotes a hoop used to bind a barrel or similar object, with figurative senses derived from its restraining function. 箍 is a character also attested in Chinese, not a character created in Japan.