EXPAN'SION, noun [Latin expansio.] The act of expanding or spreading out.

1. The state of being expanded; the enlargement of surface or bulk; dilatation. We apply expansion to surface, as the expansion of a sheet or of a lake, and to bulk, as the expansion of fluids or metals by heat; but not to a line or length without breadth.

2. Extent; space to which any thing is enlarged; also, pure space or distance between remote bodies.

3. Enlargement; as the expansion of the heart or affections.