Noun

1. The act of abstracting, separating, or withdrawing, or the state of being withdrawn; withdrawal.
   • 1848: J. S. Mill, Principles of Political Economy with some of their Applications to Social Philosophy

     The cancelling of the debt would be no destruction of wealth, but a transfer of it: a wrongful abstraction of wealth from certain members of the community, for the profit of the government, or of the tax-payers.

2. The act of leaving out of consideration one or more properties of a complex object so as to attend to others; analysis.

   Note: Abstraction is necessary to classification, by which organisms are grouped into genera and species according to the qualities they share.

   • c. 1837, Sir W. Hamilton, in Lectures on Metaphysics and Logic (1860), Lecture XXXV, page 474

     Abstraction is no positive act: it is simply the negative of attention.

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. - "[Modern]"
7. A separation of volatile parts by the act of distillation. - Nicholson
8. Removal of water from a river, lake, or aquifer, typically for industrial or agricultural uses.
9. Any generalization technique that ignores or hides details to capture some kind of commonality between different instances for the purpose of controlling the intellectual complexity of engineered systems, particularly software systems.
10. Any intellectual construct produced through the technique of abstraction.