Indivisible

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

1. That which is indivisible.
2. (Geom.) 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.