层次

layer / level / gradation / arrangement of ideas / (a person's) standing

next in sequence / second / the second (day, time etc) / secondary / vice- / sub- / infra- / inferior quality / substandard / order / sequence / hypo- (chemistry) / classifier for enumerated events: time

to pile on top of one another / layer; stratum / floor (of a building); story / (math.) sheaf / classifier for layers