keyˈhole noun

1. The hole in which a key of a lock is inserted
2. Any small hole similar in shape or purpose

keyhole limpet noun

A mollusc (genus Fissurella) with a perforated conical shell

keyhole saw noun

A padsaw (qv under pad¹)

keyhole surgery noun

Surgery using endoscopes, etc, performed through small incisions

key industry noun

An industry indispensable to others and essential to national economic welfare and independence

key light noun

The main light in a TV or film studio or on a stage

keyˈline noun (printing)

An outline drawing showing the shape, size, position, etc of an illustration

keylogging see keystroke logging below.

key man noun

An indispensable worker, essential to the continued conduct of a business, etc

key money noun

A premium, fine or sum additional to rent, demanded for the grant, renewal or continuance of a tenancy

keyˈnote noun

1. The fundamental note or tonic (music)
2. Any central principle or controlling thought

adjective

1. Of fundamental importance
2. (of a speech, etc) expounding the central principle, or setting the tone for a conference, etc

transitive verb and intransitive verb

1. To give the keynote
2. To put forward the central principle in an opening address at a convention

keyˈpad noun

1. A small device with push-button controls, eg a TV remote control unit or pocket calculator
2. A small keyboard with push-button controls for a specific purpose, eg a numeric keypad (computing)

keyˈpal noun (informal)

A person who is mainly or only known to one as an email correspondent

keyˈ-plate noun

A keyhole escutcheon

key punch noun (computing)

An obsolete device operated by a keyboard, which transfers data onto punch-cards, etc

keyˈpunch transitive verb

key ring noun

A ring for holding a bunch of keys

keyˈ-seat noun

A groove for receiving a key, to prevent one piece of machinery from turning on another

key signature noun (music)

The indication of key by marking sharps, flats or naturals where the key changes or at the beginning of a line

key stage noun (education)

Any of the four age-based levels of the National Curriculum in England and Wales

keyˈstone noun

1. The stone at the apex of an arch
2. The chief element
3. Something on which all else depends

transitive verb and intransitive verb

To produce a keystone effect, ie the distortion of a television picture in which a rectangular pattern is transformed into a trapezoidal pattern

keyˈstroke noun

A single operation of a key on a typewriter or other machine using keys

keystroke logging or keyˈlogging noun

The act of recording the keystrokes made by a computer user, eg to detect sources of error or for surveillance

keyˈstroking noun

keyˈway noun

A groove cut in a shaft or boss to accommodate a key that interlocks with another component so as to prevent relative motion

keyˈword noun

1. A headword
2. A word serving as a key in an index, etc
3. A word that encapsulates the passage in which it appears
4. A group of letters or numbers that is used to identify a database record (computing)

keyˈword-in-context adjective

Applied to electronic concordances or indexes that supply the keywords alphabetically in a fixed position in the line, preceded and followed by a fixed amount of context

keyˈworker noun

A person working in the social services who takes responsibility for individual cases and projects

have the key of the door (informal)

To have reached the age of 21

have the key of the street (informal)

1. To be locked out
2. To be homeless

key in (computing)

To enter (data) by operating a keyboard

out of key

1. Out of tune
2. Out of place, incongruous

power of the keys

The power to loose and to bind, conferred by Christ on Peter (Bible, Matthew 16.19), and claimed by the popes