noninvocable

Noninvocable is an adjective used in computer science to describe an entity that cannot be invoked, called, or executed as a function or procedure. In practice, it characterizes values or objects that do not implement a callable interface or are not exposed through a callable API. The term is often used in discussions of programming language design, libraries, and security to distinguish between items that can be executed and those that cannot.

In programming languages with first-class functions, a value is noninvocable if it is not callable—for example, a plain number or a data object that does not implement a call operation. In APIs or command interfaces, an operation may be noninvocable for external clients because it is internal, deprecated, or restricted by permissions. In type and interface design, marking something as noninvocable helps convey its role as data or state rather than behavior.

Common related terms include callable, invocable, and non-callable. The concept emphasizes the distinction between values that can be executed and those that cannot, which is important for understanding interfaces, access control, and error handling. Examples include a class instance without a __call__ method in Python, or a public method that is intentionally not exposed as part of a public API.