Other forms: hyponyms
A hyponym is a word that's defined by another word but is a lot more specific. "Cocker spaniel" is a hyponym of "dog."
In linguistics, some words, known as hypernyms, are generic "umbrella terms" that cover a wide range of things. Hyponyms, on the other hand, are specific words that fall under that umbrella. "Music" is a hypernym, and "rock and roll," "jazz," "opera," and "folk" are all hyponyms. The Greek roots of hyponym are hypo, "under," and onyma, "name."