General Cattle Terminology:
A bull is a bovine male.
A steer is a bovine male castrated prior to puberty.
A sire is a male parent.
A cow is a sexually mature female bovine that has usually produced a calf.
A heifer is a young female bovine prior to the first time that she has produced her first calf.
A dam is a female parent.
A calf is a young bovine under 1 year of age.
A pair is a calf and its mother.
A head is a single animal.
Culling is the action of eliminating one or more animals from the breeding herd.
Ruminant is a mammal whose single stomach has four parts – rumen, reticulum, omasum and abomasum.
More Cattle Industry Definitions: http://www.beefusa.org/a.aspx