IPA: //ˈkwɔːrtərˌdɛk//
KK: /ˈkwɔrtərˌdɛk/
The back section of the upper deck on a ship, typically used by officers and for official purposes.
The captain stood on the quarterdeck to address the crew before setting sail.
Quarterdeck → The word is formed from "quarter" (from Old French *quartier*, meaning a section or part) and "deck" (from Old Norse *dekk*, meaning a covering or floor). The quarterdeck refers to the part of a ship that is reserved for the captain and officers, essentially a section of the deck.
Think of a 'section' ('quarter') of the ship that is a 'covering' or 'floor' ('deck') where the captain and officers operate.