proprium

Nam unusquisque suum proprium possidet corpus, non et ουσιαν.

What Swedenborg calls 'selfhood,' the proprium, is not in him.

Thus, the defining property of an equilateral triangle is the equality of the sides: the equality of the angles is a proprium.

If simply convertible, the two must be coextensive, and the Predicate must be either a Proprium or the Definition.

And I may say of him, as was said of a celebrated poet, Cui unquam poetarum magis proprium fuit subito astro incalescere?