The Collaborative International Dictionary of English v.0.48:
Occupancy \Oc"cu*pan*cy\, n. [See Occupant.]
1. The act of taking or holding possession, especially of
real property or rental property; possession; occupation.
2. The state or condition of being occupied; as, occupancy by
more than 250 people is dangerous and unlawful.
3. The period of time during which one occupies a property.
Title by occupancy (Law), a right of property acquired by
taking the first possession of a thing, or possession of a
thing which belonged to nobody, and appropriating it.