Source : Webster's Revised Unabridged Dictionary (1913)

-ish \-ish\ [AS. -isc; akin to G. -isch, OHG. -isc, Goth. & Dan.
   -isk, Gr. ?. Cf. {-esque}.]
   A suffix used to from adjectives from nouns and from
   adjectives. It denotes relation, resemblance, similarity, and
   sometimes has a diminutive force; as, selfish, boyish,
   brutish; whitish, somewhat white.

-ish \-ish\ [OE. -issen, fr. F. -is, -iss- (found in the present
   particle, etc., of certain verbs, as finir to finish, fleurir
   to flourish), corresponding to L. -escere, an inchoative
   ending.]
   A verb ending, originally appearing in certain verbs of
   French origin; as, abolish, cherish, finish, furnish,
   garnish, impoverish.