Full Idea
A property [idion] is something which does not show the essence of a thing but belongs to it alone. ...No one calls anything a property which can possibly belong to something else.
Gist of Idea
An 'idion' belongs uniquely to a thing, but is not part of its essence
Source
Aristotle (Topics [c.331 BCE], 102a18)
Book Reference
Aristotle: 'Posterior Analytics and Topica', ed/tr. Tredennick,H/Forster,ES [Harvard 1960], p.283
A Reaction
[See Charlotte Witt 106 on this] 'Property' is clearly a bad translation for such an individual item. Witt uses 'proprium', which is a necessary but nonessential property of something. Necessity is NOT the hallmark of essence. See Idea 12266.
Related Idea
Idea 12266 'Same' is mainly for names or definitions, but also for propria, and for accidents [Aristotle]