1 make less severe or extreme; tone down (modify one's demands).
2 make partial changes in; make different.
3 Gram. qualify or expand the sense of (a word etc.).
4 Phonet. change (a vowel) by umlaut.
5 Chem. change or replace all the substituent radicals of a polymer, thereby changing its physical properties such as solubility etc. (modified starch).
Derivatives:
modifiable adj. modificatory adj.
Etymology: ME f. OF modifier f. L modificare (as MODE)
Useful english dictionary. 2012.