before, companion, same kind
疇 centers on grouping by shared nature: things of the same kind, companions, or a category. The 'before' sense is an older temporal extension of being in the same class or sequence.
疇 combines 田 (field) with 壽, which likely contributes the sound and the idea of something long-lasting or arranged. The character originally referred to field boundaries or furrows, which later extended to categories and companions.
A field 田 divided by long-lasting 壽 boundaries creates separate plots that are all of the same kind. Think of furrows that group plants into companions of the same type.
For チュウ, imagine a field of companions all chewing on the same kind of snack: chew -> チュウ, and they are all of one kind.
category
subcategorization; subcategorisation
subcategorization principle; subcategorisation principle
subcategorization feature; subcategorisation feature
grammatical category
to go over one's head; to be beyond one's comprehension
categorical grammar
syntactic category