Bringing into being; causing to exist; producing; originative; as, an age productive of great men; a spirit productive of heroic achievements.

Producing, or able to produce, in large measure; fertile; profitable.

producing or capable of producing (especially abundantly); "productive farmland"; "his productive years"; "a productive collaboration"

A form-class which is continuing to add to its membership through analogy or neologism: the -ar verb conjugation of Spanish may be described as productive because many new verbs (eg formatear, privatizar) are constantly being added to it. A form-class which has typically shown expansion at some point in the history of the language (eg the u-e 'strong' Preterites of Spanish) may be said to be semiproductive.

describes a grammatical structure, such as a word PREFIX or SUF-FIX, that can easily combine to form new words or phrases. For example, the negative prefix un-is highly productive; not only can many new words be formed with it, but other speakers of English will be able to understand the word without further explanation. You could tell a friend that your blind date last night was “very unwonderful,” and although the word is not in the dictionary and may never have been heard before, your friend would understand it immediately.

When you can use a process like reduplication or various prefixes and suffixes like ini– or –wu with lots of different roots; they have a clear meaning and you can use them with many different words.

having the ability to produce or originate; "generative power"; "generative forces"

The ability of an area to provide goods and services and to sustain ecological values. ( FS People's Glossary of Eco Mgmt Terms)

Having the quality or power of producing; yielding or furnishing results; as, productive soil; productive enterprises; productive labor, that which increases the number or amount of products.

yielding positive results

Biologically active, supporting a diversity of aquatic life.

Useful.