in Latin, a verbal noun in the singular of all cases but the nominative, used to indicate continuing or generalized action (Ex.: probandi in onus probandi, “the burden of proving”)

in other languages, any of various forms analogous of this; specif., an English verbal noun ending in -ing that has all the uses of the noun but retains certain syntactic characteristics of the verb, such as the ability to take an object or an adverbial modifier (Ex.: playing in “Playing golf is his only exercise”)