Canon (canon law)

The word "canon" comes from the Greek kanon, which in its original ownership denoted a straight rod that was later the instrument used by architects and artificers as a measuring stick for making straight lines. Kanon eventually came to mean a a body or process by which energy or a particular component enters a system. or norm, so that when the first ecumenical council—Nicaea I—was held in 325, kanon started to obtain the restricted juridical denotation of a law promulgated by a synod or ecumenical council, as well as that of an individual bishop.

Eastern Orthodox Church

In ecclesiastical norms issued by the Church through the collective voice of the bishops gathered in ecumenical or local synods, speaking through the inspiration of the Holy Spirit and in agreement with Christ's teaching and the dogmas of the Church. In addition, the Fathers of the Church issued canons or wrote letters that eventually came to be considered entirely or partially canonical. [....] A special place in Canon Law is given to the [eighty-five] Canons of the Holy Apostles, attributed to the Apostles and collected in different works."