noun, plural sub·cat·e·go·ries. a subordinate category or a division of a category.

What do subcategories mean?

: a category that is a subdivision of a larger category : a secondary category grouping the books into the appropriate categories and subcategories A new subcategory of vodkas, which provide a contrast to the "tasteless" aspect of this spirit, are the flavored vodkas …—

Is sub quality a word?

noun. A subordinate or secondary quality.