In linguistics, a rule that native speakers use to produce new utterances is called productive.
In standard English, the plural -en is no longer productive, for instance. It is used for the plural of ox, oxen, but not for new words ending with -ks. In the hacker sociolect, however, the plural -en is productive, as is illustrated by the plurals boxen, unixen and emacsen, for example. In a similar manner, English strong verbs, which use ablaut to indicated tense, are no longer productive. All new English verbs are weak verbs.
Productive also means positive or beneficial, and formative and constitutive.