Định nghĩa và ý nghĩa của "stratum"trong tiếng Anh

a distinct layer or level within a system, often conceived as having depth or hierarchy

a subpopulation divided into a stratified sampling

a group of people with similar social standing, education, or income

a distinct layer or level within a language system, such as different dialects, sociolects, or registers, that are associated with specific social groups, regions, or levels of formality