E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Rector, one who receives both great and small tithes. Vicar receives only the small tithes. At the Reformation many livings which belonged to monasteries passed into the hands of noblemen, who, not being in holy orders, had to perform the sacred offices vica-riously. The clergyman who officiated for them was called their vicar or representative, and the law enjoined that the lord should allow him to receive the use of the glebe and all tithes except those accruing from grain (such as corn, barley, oats, rye, etc.), hay, and wood.
The term Vicar is now applied to the minister of a district church, though he receives neither great nor small tithes; his stipend arising partly from endowment, partly from pew-rents, and in part from fees, voluntary contributions, offerings, and so on. The vicar of a pope is a Vicar-apostolic, and the vicar of a bishop is a curate or vicar in charge.
A lay vicar is a cathedral officer who sings certain portions of the service. The Pope is called the Vicar of Christ.