late Old English mægester "one having control or authority," from Latin magister (n.) "chief, head, director, teacher" (source of Old French maistre, French maître, Spanish and Italian maestro, Portuguese mestre, Dutchmeester, German Meister), contrastive adjective ("he who is greater") from magis (adv.) "more," from PIE *mag-yos-, comparative of root *meg- "great" (see mickle). Form influenced in Middle English by Old French cognate maistre. Meaning "original of a recording" is from 1904. In academic senses (from Medieval Latin magister) it is attested from late 14c., originally a degree conveying authority to teach in the universities. As an adjective from late 12c.
dialectal survival of Old English micel, mycel "great, intense, big, long, much, many," from Proto-Germanic *mekilaz (cf. Old Saxon mikil, Old Norse mikill, Old High German mihhil, Gothic mikils), from PIE root *meg- "great, large" (cf. Armenian mets "great;" Sanskrit mahat- "great, mazah- "greatness;" Avestan mazant- "great;" Hittite mekkish "great, large;" Greek megas "great, large;" Latin magnus "great, large, much, abundant," major"greater," maximus "greatest;" Middle Irish mag, maignech "great, large;" M.Welsh meith "long, great"). Its main modern form is much (q.v.). Related: Mickleness.