What does dependency mean?
Dependency is a noun describing the condition of relying on, being influenced by, or being subject to someone or something else. It appears across many domains: economics speaks of a nation's dependency on imports, medicine discusses drug or alcohol dependency, and politics uses the term for territories governed by another state, such as a crown dependency. In everyday language it conveys vulnerability — the idea that one's wellbeing or success rests on an external factor beyond full control — though in computing it is entirely neutral, naming any external library or module a piece of software needs to run. Related forms include the adjective dependent and the verb depend. The word carries no strong emotional charge by itself; its connotation shifts with context, from the clinical neutrality of 'codependency' in psychology to the urgency of warnings about fossil-fuel dependency. Its versatility makes it indispensable in discussions of systems, relationships, and power.
nounThe state of relying on or being controlled by someone or something else; a thing that one relies on for support or function. In computing, a component or library that another program requires in order to operate.
- The state of relying on or being under the control of someone or something else.
- A thing (such as a substance, resource, or person) that one depends on; often specifically a physical or psychological reliance on an addictive substance.
- A territory controlled by and subordinate to another country.
- In computing: an external module, library, or service that a program requires to function.
"The region's heavy dependency on imported oil left it vulnerable to price shocks."
"Economists warned that the country's dependency on a single export made it fragile."
"After years of heavy drinking, he sought help for his alcohol dependency."
The plural is common when referring to multiple items of reliance, especially software libraries or various needs.
"Before deploying the update, make sure all dependencies are installed correctly."
In software, a single 'dependency' can quietly pull in hundreds of others — a phenomenon developers call 'dependency hell'.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dependency
Dependency derives from the verb 'depend', which entered English from Old French 'dépendre', itself from Latin 'dependere' meaning 'to hang down from' or 'to be suspended from' — a vivid image of something hanging from and thus reliant on its support. The Latin root combines 'de-' ('down from') with 'pendere' ('to hang'), the same root that gives us 'pendant' and 'suspend'. The noun form emerged in English in the early 17th century, initially alongside the older variant 'dependence'; both were used interchangeably for centuries before their senses gradually diverged.
How dependency is actually used
Formal-to-neutral register. 'Dependency' is preferred over 'dependence' when referring to a countable item of reliance (a dependency in code, a colonial dependency). In medical and psychological contexts it is the standard term for substance reliance, carrying a clinical rather than judgmental tone compared with 'addiction'.
Easily confused with dependency
'Dependence' is the older, more abstract noun meaning the state of relying on something, while 'dependency' more often refers to a concrete thing relied upon (such as a territory or a software library), though the two overlap considerably.