inject

Inject is a verb meaning to push or introduce a substance into another object or system, typically by insertion or forced entry. The term is used across disciplines to describe the delivery of liquids, data, or mappings into a target medium.

In medicine, an injection refers to delivering a liquid drug or vaccine into the body using a syringe, by intramuscular, subcutaneous, or intravenous routes. Proper technique, sterility, and dosing are essential. Injections can be local or systemic and come in various formulations, including suspensions and emulsions, for different therapeutic goals.

In computing, injection refers to introducing external data or code into a program or query. Examples include SQL injection, where malicious input alters database commands, and code injection, where executable code is introduced into a process. Dependency injection is a software design pattern in which objects receive their dependencies from external sources rather than creating them internally, improving modularity and testability.

In mathematics and logic, an injective function (an injection) maps distinct elements of its domain to distinct elements of its codomain, i.e., it is one-to-one. The verb inject is occasionally used informally to say a function injects one set into another, though more precise terminology often uses “injective” or “one-to-one.”

Beyond these, injection can describe the artificial introduction of fluids into subsurface formations in geology and engineering, for purposes such as storage or enhanced oil recovery, as well as injections used in biological research and therapy to deliver substances into tissues.