riser

n 1 vertical piece between two treads of a staircase 梯级竖板. 2 person who habitually gets up early or late in the morning (as specified) 惯於早起或晚起的人: an early/a late riser 早起[晚起]的人.

riot, riot police, riot shield, riotous, riotously, riotousness, rip, rip-cord, rip-off, rip-roaring, rip-saw, rip-tide, riparian, ripe, ripen, ripeness, riposte, ripple, rise, rise superior to, risible, rising, rising damp, rising fives, risk, riskily, riskiness, risky, risotto, risque, rissole, rite, ritual, ritualize, ritzy, rival, rivalry, rive, riven, river,