In
metaphysics, particulars are, one might say, identified by what they are not: they are not
abstractions, not multiply-instantiated--i.e. they are concrete. (There are, however, theories of abstract particulars or
tropes.) Hence,
Socrates is a particular (there's only one Socrates-the-teacher-of-Plato and one cannot make copies of him, e.g., by cloning him, without introducing new, distinct particulars). Redness, by contrast, is not a particular, because (it is held by
metaphysical realists) it is abstract and multiply-instantiated (my bicycle, this apple, and that girl's hair are all red).
See more at Wikipedia.org...
PARTICOLARE. SPECIALE. ESATTO. SCRUPOLOSO. DIFFICILE. DETTAGLIO. DATO