| Definition -
The ability to say and understand new word forms or sentences that one has never heard or used before, e.g. the wug test: one wug + one wug = two wugs.
1. Forming new past tenses by using ablaut (e.g. sing–sang–sung) rarely occurs, so it is no longer considered productive.
2. Forming the past tense or past participle of newly coined verbs by using -ed is still common (e.g. spammed or e-mailed), hence is considered productive.
3. It is one of Hockett's 16 design features of language that distinguish human language from animal communication systems.
Etymology - The word derives from the Latin productus, the past participle of producere, lead, bring forth, or draw out
Oxford English Dictionary - There is no OED citation for this sense of the word.