noun
: a sprinkler system in which water is admitted to the system upon the release of air pressure that the pipes normally contain and which is used where there is danger of freezing
noun
: a sprinkler system in which water is admitted to the system upon the release of air pressure that the pipes normally contain and which is used where there is danger of freezing
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012