- (n.) The condition of rarefaction or reduction of pressure below that of the atmosphere, in a vessel, as the condenser of a steam engine, which is nearly exhausted of air or steam, etc.; as, a vacuum of 26 inches of mercury or 13 pounds per square inch.
- (n.) A space entirely devoid of matter (called also, by way of distinction, absolute vacuum); hence, in a more general sense, a space, as the interior of a closed vessel, which has been exhausted to a high or the highest degree by an air pump or other artificial means; as, water boils at a reduced temperature in a vacuum.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). vacuum. Retrieved September 23, 2026, from http://smartdefine.org/vacuum/definitions/2078523 |
| Chicago | Webster's. 2011. "vacuum" http://smartdefine.org/vacuum/definitions/2078523 (accessed September 23, 2026). |
| Harvard | Webster's 2011, vacuum, Smart Define, viewed 23 September, 2026, <http://smartdefine.org/vacuum/definitions/2078523>. |
| MLA | Webster's. "vacuum" 28 May 2011. Web. 23 September 2026. <http://smartdefine.org/vacuum/definitions/2078523> |