An archaic form marking the past participle.
[Old English ge-.]
In Old English ge- marked the past participle of words (issued, sent), as it does in modern German. By the fourteenth century, this had dwindled to y- (ybaptised, yblamed), or had vanished altogether. Writers from the fifteenth century have used it as a conscious anachronism in forms such as yclept, ‘called or named’.