Stratum

地層

chisō

(layer of sedimentary rock having approximately the same composition throughout)

層

sō

(one of several parallel horizontal layers of material arranged one on top of another)

層

sō

(any of the regions of the atmosphere)

層

sō

(layer of tissue)

階級

kaikyū

(class of society composed of people with similar social, cultural, or economic status)