1a container consisting of one or more cells, in which chemical energy is converted into electricity and used as a source of power:a camera battery [as modifier]:battery power
2a fortified emplacement for heavy guns:anti-aircraft missile batteriesa mobile battery of 105 mm guns
an artillery subunit of guns, men, and vehicles.
3a set of similar units of equipment, typically when connected together:a battery of equipment to monitor blood pressure
an extensive series, sequence, or range of things:children are given a battery of tests
4 [usually as modifier] chiefly British a series of small cages for the intensive rearing of farm animals, especially calves and poultry:battery farmingbattery hens
5 [mass noun] Law the infliction of unlawful personal violence on another person, even where the contact does no physical harm:any act which puts a person in immediate and reasonable fear of battery [count noun]:most batteries involve an assaultSee also assault and battery.
6 (the battery) Baseball the pitcher and the catcher.