An object designed to open and close a lock.

An object designed to fit between two other objects (such as a shaft and a wheel) in a mechanism and maintain their relative orientation.

A crucial step or requirement.

A guide explaining the symbols or terminology of a map or chart; a legend.

A guide to the correct answers of a worksheet or test.

One of several small, usually square buttons on a typewriter or computer keyboard, mostly corresponding to text characters.

In musical instruments, one of the valve levers used to select notes, such as a lever opening a hole on a woodwind.

In instruments with a keyboard such as an organ or piano, one of the levers, or especially the exposed front end of it, which are depressed to cause a particular sound or note to be produced.

The lowest note of a scale; keynote.

In musical theory, the total melodic and harmonic relations, which exist between the tones of an ideal scale, major or minor; tonality.

In musical theory and notation, the tonality centering in a given tone, or the several tones taken collectively, of a given scale, major or minor.

In musical notation, a sign at the head of a staff indicating the musical key.

The general pitch or tone of a sentence or utterance.

A modification of an advertisement so as to target a particular group or demographic.

An indehiscent, one-seeded fruit furnished with a wing, such as the fruit of the ash and maple; a samara.

A manual electrical switching device primarily used for the transmission of Morse code.

A piece of information (e.g. a passphrase) used to encode or decode a message or messages.

A password restricting access to an IRC channel.

In a relational database, a field used as an index into another table (not necessarily unique).

A value that uniquely identifies an entry in a container.

The free-throw lane together with the circle surrounding the free-throw line, the free-throw lane having formerly been narrower, giving the area the shape of a skeleton key hole.

A series of logically organized groups of discriminating information which aims to allow the user to correctly identify a taxon.

A piece of wood used as a wedge.

The last board of a floor when laid down.

A keystone.

That part of the plastering which is forced through between the laths and holds the rest in place.

A wooden support for a rail on the bullhead rail system.

The degree of roughness, or retention ability of a surface to have applied a liquid such as paint, or glue.

The thirty-third card of the Lenormand deck.

(print and film) The black ink layer, especially in relation to the three color layers of cyan, magenta, and yellow. See also CMYK.

A color to be masked or made transparent.

To fit (a lock) with a key.

To fit (pieces of a mechanical assembly) with a key to maintain the orientation between them.

To mark or indicate with a symbol indicating membership in a class.

(telegraphy and radio telegraphy) To depress (a telegraph key).

To operate (the transmitter switch of a two-way radio).

(more usually to key in) To enter (information) by typing on a keyboard or keypad.

To vandalize (a car, etc.) by scratching with an implement such as a key.

To link (as one might do with a key or legend).

To be identified as a certain taxon when using a key.

To modify (an advertisement) so as to target a particular group or demographic.

To attune to; to set at; to pitch.

To fasten or secure firmly; to fasten or tighten with keys or wedges.

Indispensable, supremely important.

Important, salient.

One of a string of small islands.

A stone or concrete structure on navigable water used for loading and unloading vessels; a wharf.

In the International System of Units, the base unit of mass; conceived of as the mass of one litre of water, but now defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 × 10-34 when expressed in units of kg⋅m2⋅s−1. Symbol: kg

The unit of weight such that a one-kilogram mass is also a one-kilogram weight.