Key

The word key has several uses: {{wiktionary}}

Signifier

• A key (art) features in painting and photography.
• A key (music) forms a property of a piece of music: see also key signature.
• In database design, keys refer to unique values in database rows. See primary key and related articles.
• A key frame constitutes a frame or cell in animation which serves as a guide for the other frames, or inbetweens. Usually the key framer is a more prominent artist than inbetweeners.
• An identification key can help to identify species.