(かぎ)

かぎ
noun
key, lock
tool
1. key
A metal instrument for opening a lock.
(かぎ)(わす)れた
I forgot my key.
I locked up before going out.
I lost my key and couldn't get into my house.
2. key, clue
Something crucial for solving a problem.
The key to success is effort.
I found the key to solving the problem.
I think that witness holds the key to this case.

Common expressions

Compounds

Usage

成功(せいこう)(かぎ) (the key to success) demonstrates how (かぎ) is used metaphorically for something crucial or decisive, similar to English "key."