noun space through which anything is expanded; also, pure space.
2. expansion ·noun the act of expanding or spreading out; the condition of being expanded; dilation; enlargement.
3. expansion ·noun the developed result of an indicated operation; as, the expansion of (a + b)2 is a2 + 2ab + b2.
4. expansion ·noun enlargement or extension of business transactions; ·esp., increase of the circulation of bank notes.
5. expansion ·noun that which is expanded; expanse; extend surface; as, the expansion of a sheet or of a lake; the expansion was formed of metal.
6. expansion ·noun the enlargement of the ship mathematically from a model or drawing to the full or building size, in the process of construction.
7. expansion ·noun the operation of steam in a cylinder after its communication with the boiler has been cut off, by which it continues to exert pressure upon the moving piston.