key
UK[kiː]US[kiː]
n
A small piece of shaped metal with incisions cut to fit the wards of a particular lock, which is inserted into a lock and turned to open or close it.
n
A thing that provides a means of achieving or understanding something.
n
Any of the buttons or levers pressed to operate a typewriter, computer keyboard, or musical instrument.
adj
Of crucial importance.
Etymology
The word 'key' originates from the Old English 'cǣg', which meant a metal device for locking or unlocking. Its ultimate origin is uncertain, but it is likely of Germanic origin, related to Old Frisian 'kei' or 'kēi'. The semantic development from a physical tool to a metaphor for something essential or explanatory (as in 'key to success' or 'key point') is a classic example of meaning extension based on the tool's primary function of access and control. This evolution reflects how a concrete, everyday object provides a powerful conceptual framework for abstract ideas of solution and importance.
Analysis
The word 'key' is a simplex word of Old English origin. It does not contain separable morphemes in its modern English form.
Examples
She turned the key in the lock and opened the door.
Hard work is the key to achieving your goals.
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