an enclosed space from which matter, especially air, has been partially removed so that the matter or gas remaining in the space exerts less pressure than the atmosphere (opposed to plenum).
the state or degree of exhaustion in such an enclosed space.
a space not filled or occupied; emptiness; void: The loss left a vacuum in his heart.
"to clean with a vacuum cleaner," 1922; see vacuum (n.). Related: Vacuumed; vacuuming.
vacuum
n.
1540s, "emptiness of space," from Latin vacuum "an empty space, void," noun use of neuter of vacuus "empty," related to vacare "be empty" (see vain). Properly a loan-translation of Greek kenon, literally "that which is empty." Meaning "a place emptied of air" is attested from 1650s. Vacuum tube is attested from 1859. Vacuum cleaner is from 1903; shortened form vacuum (n.) first recorded 1910.
A region of space having extremely low gas pressure relative to surrounding pressure. The air pump of a vacuum cleaner, for example, drastically reduces the air pressure inside the device, creating a vacuum; the pressure difference causes air to rush into it, carrying dust and debris along with it.
In the natural world, air will flow into regions of vacuum, giving rise to the saying “Nature abhors a vacuum.”
Note
The saying is extended informally: in politics, a lack of leadership may be referred to as a vacuum, which will presumably be filled by others rushing in.
