stratify

(verb) divide society into social classes or castes. Example: "Income distribution often stratifies a society."

(verb) form layers or strata. Example: "The rock stratifies."

(verb) develop different social levels, classes, or castes. Example: "Society stratifies when the income gap widens."

(verb) form, arrange, or deposit in layers. Examples: "The fish are stratified in barrels." "The rock was stratified by the force of the water." "A statistician stratifies the list of names according to the addresses."

(verb) render fertile and preserve by placing between layers of earth or sand. Example: "Stratify seeds."