1. Generalisation; ignoring or hiding details to capture some kind of commonality between different instances. Examples are abstract data types (the representation details are hidden), abstract syntax (the details of the concrete syntax are ignored), abstract interpretation (details are ignored to analyse specific properties).

2. <computer programming> Parameterisation, making something a function of something else. Examples are lambda abstractions (making a term into a function of some variable), higher-order functions (parameters are functions), bracket abstraction (making a term into a function of a variable).

Opposite of concretisation.

(01 Apr 1998)

1. The act of abstracting, separating, or withdrawing, or the state of being withdrawn; withdrawal. "A wrongful abstraction of wealth from certain members of the community." (J. S. Mill)

2. <psychology> The act process of leaving out of consideration one or more properties of a complex object so as to attend to others; analysis. Thus, when the mind considers the form of a tree by itself, or the colour of the leaves as separate from their size or figure, the act is called abstraction. So, also, when it considers whiteness, softness, virtue, existence, as separate from any particular objects.

Abstraction is necessary to classification, by which things are arranged in genera and species. We separate in idea the qualities of certain objects, which are of the same kind, from others which are different, in each, and arrange the objects having the same properties in a class, or collected body. "Abstraction is no positive act: it is simply the negative of attention." (Sir W. Hamilton)

3. An idea or notion of an abstract, or theoretical nature; as, to fight for mere abstractions.

4. A separation from worldly objects; a recluse life; as, a hermit's abstraction.

5. Absence or absorption of mind; inattention to present objects.

6. The taking surreptitiously for one's own use part of the property of another; purloining.

7. <chemistry> A separation of volatile parts by the act of distillation.

Origin: Cf. F. Abstraction. See Abstract.

(01 Mar 1998)