productive

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Producing or capable of producing crops, goods, or services, especially in abundance.
• adjective Marked by abundant production or achievement: synonym: fertile.
• adjective Yielding favorable or useful results; constructive.
• adjective Economics Of or involved in the creation of goods and services to produce wealth or value.
• adjective Effective in achieving specified results; originative. Used with of.
• adjective Producing mucus or sputum.
• adjective Forming new tissue.
• adjective Of or relating to the linguistic skills of speaking and writing.
• adjective Of or relating to a linguistic element or rule that can be used to form further examples of a particular feature or pattern. The English past tense suffix –ed is productive since it continues to be added to new verbs to form the past tense.

from The Century Dictionary.

• Serving to produce; having the power of producing: as, an age productive of great men.
• Fertile; producing abundant crops: as, a productive soil.
• In political economics, causing or tending to cause an increase in the quantity or quality of things of value; causing commodities to possess exchangeable value: as, productive labor.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Having the quality or power of producing; yielding or furnishing results
• adjective Bringing into being; causing to exist; producing; originative
• adjective Producing, or able to produce, in large measure; fertile; profitable.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Capable of producing something, especially in abundance; fertile
• adjective yielding good or useful results; constructive
• adjective Of, or relating to the creation of goods or services
• adjective linguistics, of an affix or word construction rule consistently applicable to any of an open set of words

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective yielding positive results
• adjective producing or capable of producing (especially abundantly)
• adjective having the ability to produce or originate
• adjective marked by great fruitfulness