bottom layer; lowest stratum
Refers to the physical or structural lowest layer of something, such as rock strata, paint layers, or organizational levels.
Fossils were discovered in the bottom layer of the stratum.
The undermost layer of this paint is blue.
lowest social class; bottom of society
Used for the lowest socioeconomic class or caste in a society. Often carries a negative or critical nuance.
He rose from the lowest stratum of society.
That system further afflicted people in the lowest class.
Compound of 最 (sai, 'most') + 下 (ka, 'lower') + 層 (sō, 'layer/stratum').