Definitions
1.verbTo increase; to make larger or supplement."The money from renting out a spare room can augment a salary."
2.verbTo grow; to increase; to become greater.
3.verbTo slow the tempo or meter, e.g. for a dramatic or stately passage.
4.verbTo increase an interval, especially the largest interval in a triad, by a half step (chromatic semitone).
5.verb(grammar) To add an augment to.