IPA: /ˈkoʊlˌfiːld/
KK: /ˈkoʊlˌfiːld/
A region where coal is found in large amounts, often used for mining.
The coalfield has been a major source of energy for the country for decades.
Coalfield → It is formed from "coal" (from Old English *cāle*, meaning a black combustible mineral) and "field" (from Old English *feld*, meaning an open land or area). The word "coalfield" refers to an area of land where coal is found and mined.
Think of an 'open area' ('field') where 'coal' is found — that's what a coalfield is.