The Chinese word for key is
钥匙

yàoshi

Translations for key and their definitions

鍵
1. key (in electronic devices)
9jiǔ鍵拼音 - 9-key pinyin (a way of pinyin using a 9-key keyboard)
2. to type
3. (chemistry) bond

钥匙
1. Simplified form of 鑰匙

键
1. Simplified form of 鍵

鑰匙
1. n. key (object designed to open and close locks)
配鑰匙shi - to get a key cut
奶奶nai 老是忘帶鑰匙shi 。 - Grandma always forgets her keys.
該死！我把我的鑰匙shi 丟了。 - Damn it! I've lost my keys.
他四處尋找丟失的鑰匙shi。 - He looked here and there for the missing keys.

锁匙
1. Simplified form of 鎖匙

調
1. to adjust; to regulate
2. to train; to tame; to drill
3. (music) to tune; to play (an instrument)
4. to recuperate under medical treatment
5. to mix; to stir; to blend
6. harmonious; matching
7. to cook; to flavour
8. to play; to display; to be rude; to be naughty
9. to take liberties with (a woman); to flirt
10. to throw; to toss
11. to transfer; to move; to shift
調走 - to be transferred (from a post or position)
12. to select; to promote
13. to send; to dispatch; to arrange; to allocate
14. to exchange; to interchange
15. to extract; to draw out; to obtain
16. to turn; to revolve
17. to calculate; to investigate
18. to show off; to resort to
19. style; form; mode
20. mood; taste
21. opinion; idea; expression
22. (linguistics) accent; tone
23. (music) tune; melody
24. (music) key; mode
A 調 - key of A
^徵zhǐ 調曲 - Tune in the Key of Zhi ((by Yu Xin))
25. (obsolete) Alternative form of 朝 (morning)
26. usage. Legge translates 調飢 as "great hunger", apparently based on Zhu Xi's glossing 調 as 「重也」 ("grave, serious").

關鍵
1. n. (literal, Classical) latch (fastening for a door); door bolt
2. n. (figurative) crux; key element; crucial point
3. adj. (figurative) crux; key; crucial; pivotal
一個關鍵細節 - a crucial detail
關鍵成果 - key results