-ing

WordReference Random House Learner's Dictionary of American English © 2025

-ing¹ ,suffix. 

1. -ing is attached to verbs to form nouns that express the action of the verb or its result, product, material, etc.:
   build + -ing → building: the art of building;
   a new building.
2. -ing is also attached to roots (other than verb roots) to form nouns:
   off + -ing → offing

.
-ing² ,suffix. 

1. -ing is attached to verbs to form the present participle of verbs:
   walk + -ing → walking: Is the baby walking yet?
   These participles are often used as adjectives:
   war + -ing → warring: warring factions.

WordReference Random House Unabridged Dictionary of American English © 2025

-ing¹ ,

1. a suffix of nouns formed from verbs, expressing the action of the verb or its result, product, material, etc. (the art of building;
   a new building;
   cotton wadding). It is also used to form nouns from words other than verbs (offing;
   shirting). Verbal nouns ending in -ing are often used attributively (the printing trade) and in forming compounds (drinking song). In some compounds (sewing machine), the first element might reasonably by regarded as the participial adjective, -ing², the compound thus meaning "a machine that sews,'' but it is commonly taken as a verbal noun, the compound being explained as "a machine for sewing.'' Cf. -ing². 

• Old English -ing, -ung Middle English

-ing² ,

1. a suffix forming the present participle of verbs (walking;
   thinking), such participles being often used as participial adjectives: warring factions. Cf. -ing¹. 

• the variant -in (usu. represented in spelling, spelled as -in’ ) continues Middle English -inde, -ende, Old English -ende Middle English -ing, -inge

Pronunciation

The common suffix -ing² can be pronounced in modern English as either (-ing) or (-in), with either the velar nasal consonant (ng), symbolized in IPA as [ŋ], or the alveolar nasal consonant (n), symbolized in IPA as [n]. The (-in) pronunciation therefore reflects the use of one nasal as against another and not, as is popularly supposed, "dropping the g,'' since no actual g-sound is involved.
Many speakers use both pronunciations, depending on the speed of utterance and the relative formality of the occasion, with (-ing) considered the more formal variant. For some educated speakers, especially in the southern United States and Britain, (-in) is in fact the more common pronunciation, while for other educated speakers, (-ing) is common in virtually all circumstances. In response to correction from perceived authorities, many American speakers who would ordinarily use (-in) at least some of the time make a conscious effort to say (-ing), even in informal circumstances.

-ing³ ,

1. a native English suffix meaning "one belonging to,'' "of the kind of,'' "one descended from,'' and sometimes having a diminutive force, formerly used in the formation of nouns: farthing;
   shilling;
   bunting;
   gelding;
   whiting. Cf. -ling¹. 

• Middle English, Old English -ing, cognate with Old Norse -ingr, -ungr, Gothic -ings

Collins Concise English Dictionary © HarperCollins Publishers::

-ing suffix:forming_nouns

1. (from verbs) the action of, process of, result of, or something connected with the verb: coming, meeting, a wedding, winnings
2. (from other nouns) something used in, consisting of, involving, etc: tubing, soldiering
3. (from other parts of speech): an outing

Etymology: Old English -ing, -ung

-ing suffix

1. forming the present participle of verbs: walking, believing
2. forming participial adjectives: a growing boy, a sinking ship
3. forming adjectives not derived from verbs: swashbuckling

Etymology: Middle English -ing, -inde, from Old English -ende

-ing suffix:forming_nouns

1. a person or thing having a certain quality or being of a certain kind: sweeting, whiting

Etymology: Old English -ing; related to Old Norse -ingr