The Vietnamese word "phân lớp" is primarily used in the context of biology and means "subclass." It refers to a category in the classification system of living organisms, where a subclass is a grouping within a class that includes organisms that share certain characteristics.
While "phân lớp" is primarily used in biological contexts, it can also be applied in other fields, such as education or sociology, where it may refer to a subclass of learners or social groups.