Definition of acre-foot:
(n) :
An English unit of land area (symbol: a. or ac.) originally denoting a day's ploughing for a yoke of oxen, now standardized as 4,840 square yards or 4,046.86 square metres.
(n) :
Any of various similar units of area in other systems.
(n) :
(informal, usually in the plural) A wide expanse.
(n) :
(informal, usually in the plural) A large quantity.
(n) :
(Chester, historical) An area of 10,240 square yards or 4 quarters.
(n) :
(obsolete) A field.