1Extremely strict and thorough, with no room for carelessness — used for tight security, careful management, or firm measures.
大事な会議の前は、会場の警備が厳重になる。
Before an important meeting, security at the venue becomes very strict.
個人情報は厳重に管理しなければならない。
Personal information must be managed strictly.
彼は上司から厳重に注意された。
He was sternly warned by his boss.
貴重品は金庫に厳重にしまっておいた。
I kept the valuables securely locked in a safe.