IPA: //sʌbˈsɛlər//
KK: /sʌbˈsɛlər/
A room or space located below ground level, often used for storage, and situated beneath another cellar.
The wine was stored in the subcellar to keep it cool and dark.
Subcellar → It is formed from "sub-" (meaning under) and "cellar" (from Old French *celier*, meaning a storeroom or cellar). The word "subcellar" refers to a space that is located under a cellar or storage area.
Think of something that is 'under' ('sub-') a 'storeroom' ('cellar') — that's why subcellar means a space beneath a cellar.