noun
natural class; natural kind
Primarily used in philosophical or taxonomic contexts to refer to a category of things that exist in nature, as opposed to artificial or conventional groupings.
生物学では、種は自然類の一例と見なされる。
In biology, species are considered an example of a natural kind.
自然類の概念は、哲学の形而上学でよく議
The concept of natural kinds is often discussed in the metaphysics of philosophy.