This is the 3291st most frequent Japanese word.
徹
"徹" means "to penetrate," "to go through," or "to be thorough."
徹底 refers to being thorough or meticulous, derived from the concept of completing something thoroughly, with 徹 influencing the depth and completion nature.
彼は仕事に対して徹底している。
He is thorough regarding his work.
徹 in 徹する means to persist or devote oneself completely, implying focus and dedication towards accomplishing something.
計画を最後まで徹することが大事です。
Sticking to the plan until the end is important.
徹夜 uses 徹 to express the idea of staying thorough through the night, indicating continuation without interruption.