Deprecation

Deprecation is the discouragement of use of something human-made, such as a linguistic term, a proper name, a feature, design, functionality, piece of code, or practice. Typically a thing previously used is deprecated because it is—or is claimed or thought to be—inferior compared to other options now available. Deprecation is thus a mechanism for future improvement. Deprecation implies that the community (generally, or a community of experts, or a professional body governing a sector or industry) has determined that future use—of the term, name, device, design, or feature—is unwise. However, it also means its replacement or removal is not required or is non-urgent.

Something may be deprecated even though past or extant applications of it might still be useful or functional in particular contexts—the goal here need not be the complete replacement of that which has been deprecated but rather an improvement on some broad metric (eg, safety) of the stock of that thing over time. Thus: deprecation of archaic terms to obtain consistency and readability in language/terminology; deprecation of obsolete electrical components to improve safety and compatibility in the housing stock; or deprecation of certain shared code to improve an open-source software project.^[1]

Deprecation typically implies or foreshadows a phasing out, a withdrawal or removal from availability, or a discontinuance of use or support, at some time in the future.

In general English usage, the verb "to deprecate" means "to express disapproval of (something)". It derives from the Latindeponent verbdeprecari, meaning "to ward off (a disaster) by prayer".

An early, documented usage of "deprecate" in the relevant sense is in Usenet posts in 1984, referring to obsolete features in 4.2BSD and the Cprogramming language.^[2] An expanded definition of "deprecate" was cited in the Jargon File in its 1991 revision,^[3] and similar definitions are found in commercial software documentation from 2014^[1] and 2023.^[4]

Deprecation is an improvement mechanism commonly used in software development, particularly where projects involve a large community of users or coders, or have long or complex development histories, or are rapidly iterating (thus generating more supersedence).

While a deprecated software feature remains in the software, its use may raise warning messages recommending alternatives or alternative practices. Deprecated status may also indicate the feature will be removed in the future. Features are deprecated, rather than immediately removed, to provide backward compatibility and to give programmers time to bring affected code into compliance with a new standard.

Notable reasons for deprecation include:

A building code example is the use of ungrounded ("2-prong") electrical receptacles (UK English: "unearthed"). Over time, these older devices were widely deprecated in favor of safer grounded ("3-prong") receptacles. The older, ungrounded receptacles were still permitted in many places by "grandfathering" them in existing electrical wiring, while prohibiting them for new installations. Sales and usage of ungrounded receptacles thus declined; and, if they were even still available for legal purchase in a location, they would be seen as obsolete, and would generally be intended only for repairs to existing, older electrical installations.

In technical standards, use of a certain clause may be discouraged or superseded by new clauses. As an example, in the Ethernet standard IEEE 802.3-2012, parts of Clause 5 (Layer Management) are deprecated or superseded by Clause 30 (Management).

In writing and editing, usage of a word may be deprecated because it is ambiguous, confusing, or offensive to audiences or certain members thereof. For example, the words sanction and inflammable may be misinterpreted because they have auto-antonymic or self-contradictory meanings; writing style guides often recommend substituting other words that are clearly understood and unambiguous. Some words, or word usages (meanings), that have acquired different connotations over time (such as gay, or colored), may be deprecated to avoid issues (or distraction) due to ambiguity, obsolescence or offense.

Deprecation may also occur when a technical or scientific term becomes incorrect or obsolete, either through change or supersession or further scientific discovery or the development of new scientific consensus. An example from paleontology is the previous (and now discontinued) deprecation of the term Brontosaurus in favor of the genus Apatosaurus (which Brontosaurus was, for a time, thought to be a part of).^[11][12]

Some deprecated terms in medicine are consumption (tuberculosis), grippe (influenza), and apoplexy (stroke). Superseded or misleading names of medical conditions or diseases are often deprecated, in order to avoid confusion, stigma, or misunderstandings about their risks (eg, "gay related immune deficiency syndrome", the initial term for HIV-AIDS, was erroneous and discriminatory and quickly deprecated).

In chemical nomenclature, the international standards organization IUPAC (International Union of Pure and Applied Chemistry) has deprecated the term "methyl ethyl ketone", and now recommends using the term "ethyl methyl ketone" instead.^[13]

• Abandonware
• Grandfather clause
• List of deprecated terms for diseases
• Obsolescence
• Orphaned technology

• How and When To Deprecate APIs from the JDK 5.0 Documentation