Meaning of VACUUM in English
( 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.
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012