hyponym
noun [ C ] LANGUAGE specialized
US /ˈhaɪ.pə.nɪm/ UK /ˈhaɪ.pə.nɪm/
a word whose meaning is included in the meaning of another word:
"consolidation" is a hyponym of "lung"
"heart" is a hyponym of "mediastinum"
"steatosis" is a hyponym of "liver"