Indivisible

01 a. Not divisible; incapable of being divided, separated, or broken; not separable into parts.

1.
Not divisible; incapable of being divided, separated, or broken; not separable into parts.
2.
Not capable of exact division, as one quantity by another; incommensurable.(Math.)

02 n. That which is indivisible.

1.
That which is indivisible.
“By atom, nobody will imagine we intend to express a perfect indivisible, but only the least sort of natural bodies.” — Digby.
2.
An infinitely small quantity which is assumed to admit of no further division.(Geom.)

Phrases & compounds

Method of indivisibles — a kind of calculus, formerly in use, in which lines were considered as made up of an infinite number of points; surfaces, as made up of an infinite number of lines; and volumes, as made up of an infinite number of surfaces.