1610s, "serving to produce," from French productif (16c.) and directly from Medieval Latin productivus "fit for production," from Latin product-, past-participle stem of producere "bring forth" (see produce (v.)). Meaning "fertile, producing abundantly" is by 1706. Related: Productively; productiveness.
word-forming element making abstract nouns from adjectives and meaning "condition or quality of being ______," from Middle English -ite, from Old French -ete (Modern French -ité) and directly from Latin -itatem (nominative -itas), suffix denoting state or condition, composed of -i- (from the stem or else a connective) + the common abstract suffix -tas (see -ty (2)).
Roughly, the word in -ity usually means the quality of being what the adjective describes, or concretely an instance of the quality, or collectively all the instances; & the word in -ism means the disposition, or collectively all those who feel it. [Fowler]
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Harper, D. (n.d.). Etymology of productivity. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/productivity