20kWEB: Origin of the Y- prefix. Etymology of the Y- prefix. Dictionary of Etymology.

Y-, prefix. (E.) This prefix is nearly obsolete, being only retained in the archaic words y-clept, y-wis. The M. E. forms are y-, i-; the latter being frequently written I (as a capital).—A. S. ge-, an extremely common prefix, both of sbs. and verbs. [In verbs it was prefixed, not only to the pp. (as in mod. G. and in Middle-English), but also to the past tense, to the infinitive, or indeed occasionally to any part of the verb, without appreciably affecting the sense. In the word y-wis, certainly, many editors have ignorantly mistaken it for the pronoun I; see Ywis. It appears as e- in the word e-nough; and as a- in the word a-ware.] + Du. ge-, prefix. + G. ge-; O.H.G. ka-, ki-. + Goth. ga-. Perhaps the same as the Gk. enclitic -γέ, and Skt. ha (Vedic gha), a particle laying a stress on the preceding word (as γέ), or without a distinct signification; Benfey, p. 1101; Fick, iii. 95.

Etymology Dictionary

Origin and Etymology of the Y- prefix.