also: こさい
na-adjective, noun
large and small matters; particulars; details
Rare literary word covering both big and small aspects of a matter; used for exhaustive details or circumstances. Modern Japanese prefers 詳細 or 一部始終.
事件の巨細を報告する。
Report the details of the incident.
彼はその計画の巨細を知り尽くしている。
He knows every particular of the plan.
Compound of 巨 (large) and 細 (small), literally 'large and small', extended to mean 'all matters, details'. The exact historical derivation is uncertain.