The ing's the thing:
-ing1
suffix, forming nouns
1 formed from a verb: usually expressing the action of that verb, its result, product or something relating to it, etc o building o driving o lining o washing.
2 formed from a noun: describing something made of, used in, etc the specified thing o guttering o roofing o bedding.
3 formed from an adverb: o offing o outing.
[Anglo-Saxon -ing or -ung.]
-ing2
suffix used to form
1 the present participle of verbs, as in I was only asking and saw you walking in the park.
2 adjectives derived from present participles, eg charming, terrifying.
[Anglo-Saxon as -ende.]
-ing3
suffix (no longer productive), forming nouns, signifying one belonging to a specified kind, etc or one of the same kind of quality, character, etc o gelding o whiting. Also used formerly as a diminutive, etc (compare -ling) o farthing.
[Anglo-Saxon.]
Thank-you Mr. Chambers.