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under (guidance, supervision, rules, the law, etc.)
under (a flag, the sun, etc.); beneath
with (e.g. one blow); on (the promise, condition, assumption, etc. that ...); in (e.g. the name of ...)
(someone's) side; (someone's) location
「下」 has other readings with different meanings.
先生のもとで学んでいる。
I am studying under the teacher.
厳しい規則のもとで仕事をしている。
I work under strict rules.
彼のもとには全国から多くの弟子が集まってきた。
Many disciples gathered from all over the country under him.