Definition of "Modification" :

noun: the act of making something different (as e.g. the size of a garment)

noun: slightly modified copy; not an exact copy

"A modification of last year's model."

noun: an event that occurs when something passes from one state or phase to another

"The neighborhood had undergone few modifications since his last visit years ago."

noun: the grammatical relation that exists when a word qualifies the meaning of the phrase