Available Definitions:
1) adv. - On, or to, one side; out of a straight line, course, or direction; at a little distance from the rest; out of the way; apart.
2) adv. - Out of one's thoughts; off; away; as, to put aside gloomy thoughts.
3) adv. - So as to be heard by others; privately.
4) n. - Something spoken aside; as, a remark made by a stageplayer which the other players are not supposed to hear.