Definitions for "Configuration item"
A CI is any component of an IT Infrastructure, including a documentary item such as SLA or an RFC, which is (or is to be) under the control of Configuration Management and therefore subject to formal Change control. The lowest level CI is normally the smallest unit that will be changed independently of other components. CIs may vary widely in complexity, size and type, from an entire service (including all its hardware, software, documentation, etc.) to a single program module or a minor hardware component. All existing or potential service Problems will be capable of being linked to one or more CIs.
(IEEE) An aggregation of hardware, software, or both that is designated for configuration management and treated as a single entity in the configuration management process. See: software element.
(CI). A configuration item (CI) can be defined as an aggregation of hardware and software that satisfies an end-use function, whose requirements are specified and designated for separate configuration management (based on EIA/IS-632 definition).
an instance of a physical, logical or conceptual entity that is part of your environment and has configurable attributes specific to that instance