I. noun suffix
Etymology: Middle English, from Old English -ung, -ing, suffix forming nouns from verbs; akin to Old High German -ung, suffix forming nouns from verbs
1. action or process <running> <sleeping> ; instance of an action or process <a meeting> 2. a. product or result of an action or process <an engraving> — often in plural <earnings> b. something used in an action or process <a bed covering> <the lining of a coat> 3. action or process connected with (a specified thing) <boating> 4. something connected with, consisting of, or used in making (a specified thing) <scaffolding> <shirting> 5. something related to (a specified concept) <offing> II. noun suffix Etymology: Middle English, from Old English -ing, -ung; akin to Old High German -ing one of a (specified) kind one of a (specified) kind <sweeting> III. verb suffix or adjective suffix Etymology: Middle English, probably from 1-ing — used to form the present participle <sailing> and sometimes to form an adjective resembling a present participle but not derived from a verb <swashbuckling> Usage: Though the pronunciation of -ing with the consonant \n\, misleadingly referred to as “dropping the g,” is often deprecated, this pronunciation is frequently heard. It is not known for certain why the Middle English present participle ending -ende was replaced by -ing. Analogy with the earlier noun suffix -ing probably had something to do with it. In early Modern English, present participles were regularly formed with -ing pronounced \iŋg\ (as can still be heard in a few dialects) and later \iŋ\. Evidence also shows that some speakers used \in\ and by the 18th century this pronunciation became widespread. Though teachers (with some success) campaigned against it, \in\ remained a feature of the speech of many of the best speakers in Britain and the United States well into the 20th century. It has by now lost its respectability, at least when attention is drawn to it, but throughout the United States it persists largely unnoticed and in some dialects it predominates over \iŋ\.
New Collegiate Dictionary. 2001.