stair,stairs,staircase,step,stairway 这五个词都有楼梯的意思,有什么不同吗?

stair,n.1.(阶梯等的)一级,梯级2.[用复数,用作单数或复数]阶梯,楼梯3.[用复数]【船舶学】浮动平台4.阶梯,途径stair [stεə] n.support consisting of a place to rest the foot while ascending or descending ...