The Greek word is πέταγον, which occurs in the LXX. as the technical term for the plate or diadem of the high priest (cr. Ex. xxviii. 36, &c.). What is meant by the word in the present connection is uncertain. Epiphanius (Hær. LXXVII. 14) says the same thing of James, the brother of the Lord. But neither James nor John was a Jewish priest, and therefore the words can be taken literally in neither case. Valesius and others have thought that John and James, and perhaps others of the apostles, actually wore something resembling the diadem of the high priest; but this is not at all probable. The words are either to be taken in a purely figurative sense, as meaning that John bore the character of a priest,—i.e. the high priest of Christ as his most beloved disciple,—or, as Hefele suggests, the report is to be regarded as a mythical tradition which arose after the second Jewish war. See Kraus’ Real-Encyclopædie der christlichen Alterthümer, Band II. p. 212 sq.