unities Hear it!

unities Law Definition

n

A legal fiction left over from common law—a creation of a unity for joint tenancy or ownership. The four unities are interest, possession, time, and title. See also joint tenancy. 
unity of interest
Requires that each and every joint tenant’s interests are identical in kind, breadth, and time.
unity of possession
The necessity that each joint tenant must be entitled to possess the whole property in its entirety.
unity of time
The necessity that all joint tenants’ individual interests must vest simultaneously.
unity of title
Requires that all joint tenants acquire their interests by means of a single document.