The register of a voice or instrument is the range within which it can produce notes of the same pitch. It is influenced by factors such as the shape of the mouth, the size of the larynx and the throat, the type of instrument used (clarinet, flute, saxophone), and the style of play. The register is sometimes distinguished from the timbre or tone, which refers to the quality of sound produced by an instrument.
The term register is also a sociolinguistic concept with several different meanings: in writing, it describes the style of language used, and in speaking, it describes how a person adapts their voice to fit a particular context. For example, a formal register is typically associated with a standardised version of English and is used in situations such as meetings with people who hold authority or whose jobs require respect, such as headteachers and police officers. A casual register may be more appropriate for conversation with close friends and family.
In computing, a register is a small unit of fast storage memory within a computer’s central processing unit (CPU) that holds data the CPU requires for immediate processing during arithmetic logic and other processing operations. It is made up of flip-flops and increases the performance of the CPU, although it can be expensive.
A register can also refer to an official list of names or events, or a record of charges. It can also be a device such as a cash register or a ledger for recording fares paid, money deposited and so on. The verb register is most commonly used in the sense of ‘to enter in a register’, or ‘to sign-up for something’. It is an archaic word that was once spelled as registere, but has now been standardised to registrar.
The noun register dates back to the 14th century and was derived from Middle Dutch, French and Medieval Latin registrum, the plural of a Latin word meaning ‘document’. It is closely related to the noun database and its many variants, which are based on the same core definition: an organised list or record of information. The noun register can also be applied to other systems of recording, such as a library, a collection or an archive. The register of voters is an example of a politically charged usage that predates the more general sense of the noun.