(category theory) An object which has a distinguished global element (which may be called z, for “zero”) and a distinguished endomorphism (which may be called s, for “successor”) such that iterated compositions of s upon z (i.e., sⁿ∘z) yields other global elements of the same object which correspond to the natural numbers (sⁿ∘z↔n). Such object has the universal property that for any other object with a distinguished global element (call it z’) and a distinguished endomorphism (call it s’), there is a unique morphism (call it φ) from the given object to the other object which maps z to z’ (𝜙∘z=z') and which commutes with s; i.e., 𝜙∘s=s'∘𝜙.

(software) An individual database in the versioning software ClearCase.

(architecture, computing, design) A behavioural design pattern that describes the uses of null objects and their behavior (or the lack of them).

(programming, languages) An entity that can be constructed at run-time, passed as a parameter, returned from a function, or assigned into a variable.

(programming, languages) An entity of which the value can neither be passed as a parameter, nor be returned from a function, nor assigned to a variable. (Used by Raphael Finkel, the first-class object does not need to have run-time constructability according to his definition.)

(programming, languages) An entity of which the value can be passed as a parameter, but that can neither be returned from a function, nor be assigned to a variable. (Used by Raphael Finkel, the first-class object does not need to have run-time constructability according to his definition.)

(software, object-oriented programming) An adapter pattern where the adapter contains an instance of the class it wraps.

plural of object adapter pattern

(astronomy) a type of active galaxy with an active galactic nucleus (AGN), named after its prototype, BL Lacertae

(astronomy) A near-Earth asteroid or comet with an orbit such that it has the potential to make close approaches to the Earth and is of a size large enough to cause significant regional damage in the event of impact.