Y-

CIDE DICTIONARY

Y-,  [OE. y-, i-, AS. ge-, akin to D. & G. ge-, OHG. gi-, ga-, Goth. ga-, and perhaps to Latin con-; originally meaning, together. Cf. Com-, Aware, Enough, Handiwork, Ywis.].

 A prefix of obscure meaning, originally used with verbs, adverbs, adjectives, nouns, and pronouns. In the Middle English period, it was little employed except with verbs, being chiefly used with past participles, though occasionally with the infinitive. Ycleped, or yclept, is perhaps the only word not entirely obsolete which shows this use.  [1913 Webster]
"That no wight mighte it see neither yheere."  [1913 Webster]
"Neither to ben yburied nor ybrent."  [1913 Webster]

OXFORD DICTIONARY

Y-, prefix archaic forming past participles, collective nouns, etc. (yclept).

Etymology

OE ge- f. Gmc