A particular stretch, extent, or area of ground, surface, sky, etc.; an expanse. Also figurative. Cf. open space, n. With of.

(a) The means of sallying forth. (b) The extent of ground covered, range (of a person's activity, also of a chain of mountains).

= extension, n.

the quality or condition of being extended.

Extent; space to which anything is extended.

The fact or condition of extending or reaching to a certain distance or in a certain direction.

Geometry. The action of mapping a curved surface (esp. that of a cylinder or cone) onto a plane surface in such a way that no distortions or…

The quality of having (a certain) extension; in Psychology of the breadth of sensation, as opposed to intensity (see quot. 1886).