[mass noun]the action of encrusting or state of being encrusted 包外壳;结壳 ■[count noun]a crust or hard coating on the surface of something 硬壳 ■[count noun](Architecture)a facing of marble on a building (建筑)(建筑物的)大理石表面
语源
early 17th cent. (originally as incrustation): from late Latin incrustatio(n-), from the verb incrustare (see encrust)