top of the inning, top - the first half of an inning; while the visiting team is at bat; "a relief pitcher took over in the top of the fifth"

bottom of the inning, bottom - the second half of an inning; while the home team is at bat

period of play, playing period, play - (in games or plays or other performances) the time during which play proceeds; "rain stopped play in the 4th inning"