constituting number fifteen in a sequence; 15th 第十五 August the fifteenth. 8月15号。 the fifteenth century. 15世纪。 on the fifteenth floor. 在15楼。 ■(a fifteenth/one fifteenth)each of fifteen equal parts into which something is or may be divided 十五分之一 ■an organ stop sounding a register of pipes two octaves (fifteen notes) above the diapason 十五度;十五度音栓