The term "normal to stratification" refers to something that is common or typical in a social hierarchy or structure. Synonyms for this phrase could include "standard within the hierarchy," "usual in the stratified system," or "conventional in the social structure." Other possible synonyms might include "typical of the class system," "regular within the stratified order," or "expected in the hierarchy." These words all convey the idea that the particular feature or trait in question is a common or expected part of the social structure, and is not unusual or unexpected.