Indivisible

Part of speech: noun (n.)

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. 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.

Part of speech: adjective (a.)

1. Not divisible; incapable of being divided, separated, or broken; not separable into parts. "One indivisible point of time." Dryden.

2. Not capable of exact division, as one quantity by another; incommensurable.