The Collaborative International Dictionary of English v.0.48:

Altarage \Al"tar*age\, n. [Cf. OF. auterage, autelage.]
   1. The offerings made upon the altar, or to a church.
      [1913 Webster]

   2. The profit which accrues to the priest, by reason of the
      altar, from the small tithes. --Shipley.
      [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

ALTARAGE, eccl. law. Offerings made on the altar; all profits which accrue
to the priest by means of the altar. Ayl. Par. 61; 2 Cro. 516.