Particular

In metaphysics, particulars are, one might say, identified by what they are not: they are not abstract, not multiply instantiated. 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).

Particulars might (or might not) be all individuals. At any rate, they are certainly all concrete.