return day n: a day when a return is to be made: as
a : a day on which the defendant in an action or proceeding is to appear in court (as for arraignment)
b : a day on which the defendant in an action must file an answer
c : a day on which a hearing on an action or proceeding (as a motion) is to be held
d : a day on which proof of service must be returned
e : a day fixed by law for the canvassing of election returns called also return date
Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.