中尉(zhōng wèi) - lieutenant (military rank) in Mandarin

中尉 is the middle rung of the three junior officer ranks, which are built on the same 尉 element: 少尉 (second lieutenant), 中尉 (lieutenant), 上尉 (captain). The pattern 少 / 中 / 上 repeats one level up for field officers too, giving 少校, 中校, 上校.

Learn the three prefixes once and the whole rank ladder falls out. 少 is the junior grade, 中 the middle, 上 the senior. That is far less work than memorising each rank as an unrelated word.

For English speakers the trap is the translation itself: British and American armies map their ranks onto 尉 and 校 differently, so 中尉 shows up in subtitles as both "lieutenant" and "first lieutenant". The Chinese word is stable; the English is what wobbles.