Is it ensure, insure, or assure?
mid-14c., "act or fact of possessing, a taking possession, occupation," also "thing possessed, that which is possessed," from Old French possession "fact of having and holding; what is possessed;" also "demonic possession," and directly from Latin possessionem (nominative possessio), noun of action from past participle stem of possidere "to possess" (see possess). Legal property sense is earliest; demonic sense first recorded 1580s. Phrase possession is nine (or eleven) points of the law is out of a supposed 10 (or 12). With eleven from 1640s; with nine from 1690s.
The state of having illegal drugs (1970+)
in law, the acquisition of either a considerable degree of physical control over a physical thing, such as land or chattel, or the legal right to control intangible property, such as a credit-with the definite intention of ownership. With respect to land and chattel, possession may well have started as a physical fact, but possession today is often an abstraction. A servant or an employee, for instance, may have custody of an object, but he does not have possession; his employer does, even though he may be thousands of miles from the object he owns. Furthermore, except in the most abstract way, it is not possible to speak of the possession of intangible property.