Definition from Wiktionary, the free dictionary
See also Appendix:Variations of "y"
Middle English 
From Old English ġe- (perfective and associative prefix), from unstressed Proto-Germanic *ga-. Cognate with Old Saxon gi-, Dutch ge-, Old High German ga- (German ge-), Old Norse g-, Gothic 𐌲𐌰- (ga-). See also ker-.
Alternative forms 
- Used with past participle conjugations to form past participles (this prefix does not occur independently).
Derived terms 
Usage notes 
- Not productive in Modern English.
- This prefix represents a common Germanic collective prefix, as well as a perfective prefix which was used to form past participles. Already by the Old English period such participles could be used with or without it, and as it passed into Middle English forms y-, i-, and ȝe-, it became less productive. The prefix was later adopted as a conscious archaism by some writers such as Edmund Spenser, who prepended it to existing past participles.
See also 
- ẏ, Middle English abbreviation for þe
- Middle English, y- (prefix) is often confused with ye (pronoun) or with þe (the) or ye (article, definite) and the thorn þ due to typographic variation: