un-, mis-, Irish, Old Irish mí-, root mî, mei, mi, lessen; Greek $$Gmeíwn, less; Latin minus, less; English mis-, Gothic missa- (*miþ;to-). See maoth, mìn. Stokes makes mí- a comparative like $$Gmeíwn, and rejects the Teutonic words.
Etymological dictionary of the Gaelic language.
Alexander Gairm Publications.
1982.