CANON, in an ecclesiastical sense, is a law or rule, either of doctrine or discipline, enacted especially by a council, and confirmed by the authority of the sovereign.
Canons are properly decisions of matters of religion; or regulations of the policy and discipline of a church, made by councils, either general, national, or provincial. Such are the canons of the council of Nice, or Trent, &c.
There have been various collections of the canons of the eastern councils; but four principal ones, each ampler than the preceding. The first, according to Usher, A. D. 380, containing only those of the first ecumenical council, and the first provincial ones: they were but 164 in number. To these, Dionysius Exiguus, in the year 520, added the 50 canons of the apostles, and those of the other general councils. The Greek canons in this second collection end with those of the council of Chalcedon; to which are subjoined those of the council of Sardica, and the African councils. The fourth and last collection comes down as low as the second council of Nice; and it is on this that Balsamon and Zonaras have commented.