Word Origin & History
suffix attached to verbs to mean their action, result, product, material, etc., from O.E. -ing, -ung, from P.Gmc. *unga (cf. O.N. -ing, Du. -ing, Ger. -ung). Originally used to form nouns from verbs and to denote completed or habitual action. Its use has been greatly expanded in M.E. and Mod.Eng. The
other use of -ing is to form the prp. of verbs, and in this sense it developed from O.E. -ende (cf. Ger. -end, Goth. -and, Skt. -ant, Gk. -on, L. -ans). It evolved into -ing in 13c.-14c.