The suffix -ing is pronounced as [Iŋ], but sometimes also weakened to [əŋ]. The suffix does not bear stress. All -ing derivations have common gender, and hence take the definite article de.

Derivation of nouns with a verbal base is productive. Examples are given in the table below:

With respect to verbal bases, derivations in -ing may often be strict action nouns, just like the nominal infinitives in -en. However, in order to derive action nouns Frisian has a very strong preference for the nominal infinitive. This is in contrast to Dutch, in which this preference is much weaker, if it exists at all. Compare the following sentences in which Dutch and Frisian examples are given:

In contrast to nominal infinitives in -en, derivations in -ing undergo semantic specialisation on a large scale. In Frisian this is even clearer than in Dutch, due to the fact that the portion of Frisian -ing-derivations that is used as absolute action nouns is limited. So, next to the -ing-derivations which express an action noun proper, one can find derivations which denote the agent of the action, for example as in bewegingmovement, betsjinningservice or ferieningsociety. Examples of derivations denoting the patient an action are uteringutterance, oersettingtranslation and útstallingexhibition. Instrument names are fredingfence, fuorringlining or ferwaarmingheater.

In a few cases, the suffix -ing can derive nouns on the basis of other nouns. The most important examples are the following:

Although this is not quite clear in all the existing cases, the semantic contribution seems to be something like collectiveness. The words huzinghousing and hiemingyard are used especially in a legal context.

Derivation of -ing from an adjectival base is even rarer. The clearest example is fêstfixed > fêstingfortress, although it is questionable whether this derivation is transparant for all speakers. An example in the same semantic vein is feiligingprotection from feilichsave. Alternatively, it could also be argued that such formations are derived from the verbs fêstjeto fix and feiligjeto protect. Such verbs could have been derived by way of conversion from the adjectives fêstfixed and feilichsave, respectively.

There is only one example in which we see an adverb functioning as base: deldown > dellingvalley.

In a number of cases, the base form of the derivation is opaque. Examples are huninghoney, keningking, hjerringherring, gadingtaste and fellingrim.

The suffix -ing has a variant -inge, which, however, will now be obsolete in the spoken language. In the written language the variant -inge belongs to the elevated style. Next to for example wijingconsecration (< wijeto consecrate), haaiïnghaymaking (< haaieto make hay) and huzinghousing (< hûshouse) one can find the forms wijingeconsecration, haaiïngehaymaking and huzingehousing. In a few cases, the variant -inge is lexicalized and therefore has survived, for example rispingeharvest, from rispjeto harvest (but also rispingharvest exists) and printingeprinting, from the verb printsjeto print. The noun tyngenews is a shortening (with deletion of medial /d/) of tidingenews.

In some derivations in which the base form ends in /k/ or /g/, the suffix -ing is replaced by, or possibly reanalyzed as -en, possibly as a result of dissimilation. Thus next to bokkingkipper we can find bokkenkipper, next to sigingbreeze we have sigenbreeze (< siigjeto breeze) and instead of *hantrekking we find hantrekkenhelping hand.

It seems that derivations in -ing can be blocked by other action nouns. One could argue that words like *komming, *dwaning and *farring are unacceptable because of the existence of formations like komstarrival, diedaction and feartspeed, respectively.

The fact that -ing derivations undergo competition from such lexicalized action nouns might be a consequence of their inherent tendency towards lexicalization. If contrastive pairs of -ing derivations with a different lexicalized action noun are found, then there is often a semantic or stylistic difference. Compare for example ropcall with roppingvocation, brekbreak with brekkingbreaking, winstprofit with winningextraction and ferjeffenisforgiveness with ferjouwingforgiveness.

Nouns ending in -ing regularly take the allomorph -kje as their diminutive suffix, e.g. hjerringherring > hjerrinkje. As to pluralization, both plural suffixes, i.e. -en and -s, are possible. More information on this issue, with additional literature, can be found variation of -en and -s.