The OED's earliest entries for college are of
An organized society of persons performing certain common functions and possessing special rights and privileges; a body of colleagues, a guild, fellowship, association
as in John Wyclif's The Clergy May Not Hold Property, ca. 1380:
criste and his colage myȝt not be dispensid wiþ
in reference to the Apostles. Not long thereafter are found examples of its use to refer to any collective body, for example in John Capgrave's mid-15th century Life of Saint Katherine, at 1821:
O Ihesu most swettest, whiche hast noumbred me Right in þi college a-mongis þi maydenes alle
Prominent among the various colleges in British society at the time were communities or corporations formed for mutual support: houses for clergy, for instance, or almshouses. An example given is Morden College, originally "an asylum for decayed merchants." In Chambers' Cyclopædia, similarly,the entry for Colleges for disabled Soldiers, Seamen &c. is a simple cross-reference: See Hospitals.
And so we find the OED's first entry for college as a community of scholars as follows:
- A society of scholars incorporated within, or in connection with, a University, or otherwise formed for purposes of study or instruction:
a. esp. An independent self-governing corporation or society (usually founded for the maintenance of poor students) in a University, as the College of the Sorbonne in the ancient University of Paris, and the ancient colleges of Oxford and Cambridge.
b. A foundation of the same kind, outside a University. (Often combining, in its original character, the functions of a local charity for the aged and of eleemosynary education for the young.)
(emphasis added). The earliest English-language entry given here is from about 1530: In the Unyversyte Off Oxynfurde scho gert be A collage fowndyt, in Andrew of Wyntoun's Ðe orygynale cronykil of Scotland.
Thence came the other meanings of college related to academia: as a synonym for university education in Scotland and the U.S. (as I note elsewhere), as subdivisions of universities, as institutions of advanced training, as buildings occupied by any of those bodies, and so forth.