c.1500, in philosophy, from Middle French modification (14c.) and directly from Latin modificationem (nominative modificatio) "a measuring," noun of action from past participle stem of modificare (see modify). Meaning "alteration to an object to bring it up to date" is from 1774. Biological sense is attested by 1896.
modification mod·i·fi·ca·tion (mŏd'ə-fĭ-kā'shən)
Any of the changes in an organism that are caused by environment or activity and are not genetically transmissable to offspring.