Definition of Allen key in English:

Allen key

(US Allen wrench)


  • A spanner designed to fit into and turn an Allen screw.

    • ‘Attaching the back of the chair to the seat took me a good hour, wrestling in equal measure with an Allen key, the various chair components and an over-eager cat given to chasing small parts and hiding screwdrivers.’
    • ‘Packing a small adjustable spanner and a set of Allen keys will make sure you can do those last-minute running repairs.’
    • ‘After much work with an Allen wrench the Wookie tightened the wheel enough to make it catch and then, by holding his tongue the right way and not breathing too much, spliced the rotten wires together.’
    • ‘Presumably it arrived in a flat pack with instructions and an Allen key.’
    • ‘However, there are some differences in how the blades are changed, ranging from a hex-head set screw that requires an Allen wrench to a simple flip-lever design that does need a tool.’


1960s: from the name of the manufacturer, the Allen Manufacturing Company, of Hartford, Connecticut.


Allen key

/ˈalən kiː/