Definition of Effluxion of Time
When this phrase is used in leases, conveyances, and other like deeds, or in agreements expressed in simple writing, it indicates the conclusion or expiration of an agreed term of years specified in the deed or writing, such conclusion or expiration arising in the natural course of events, in contradistinction to the determination of the term by the acts of the parties or by some unexpected or unusual incident or other sudden event.
That's the definition of Effluxion of Time in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.