Homonym: KEY (Musical)
A "KEY" is a small, typically metal instrument used to open or close locks. It has a unique shape that corresponds to the specific mechanism of a lock, allowing it to turn and disengage the locking mechanism. Keys can also be used for various purposes, such as starting vehicles or securing cabinets.
In addition to physical keys, the term "key" can refer to important concepts or elements in different contexts. For example, in music, a key determines the scale and tonality of a piece. In computer science, a key can refer to a unique identifier in a database, such as a primary key that ensures each record is distinct.