[spi.rea] or spi.raea n [NL Spiraea, fr. L, a plant, fr. Gk speiraia] (1669) 1: any of a genus (Spiraea) of shrubs of the rose family with small perfect usu. white or pink flowers in dense racemes, corymbs, cymes, or panicles
2: any of several garden plants resembling spireas; esp: a shrub (Astilbe japonica) of the saxifrage family