IPA: /ˈrɪdʒˌpoʊl/
KK: /ˈrɪdʒpoʊl/
A horizontal beam at the top of a roof that supports the rafters, or the top pole of a tent.
The carpenter installed the ridgepole to ensure the roof was stable.
Ridgepole → It is formed from "ridge" (from Old English *hrycg*, meaning the top or highest point of something) and "pole" (from Old English *pal*, meaning a long, slender piece of wood). The word "ridgepole" refers to the horizontal beam at the top of a roof structure that supports the roof's ridge.
Think of the 'top' ('ridge') of a structure being supported by a 'long piece of wood' ('pole') — that's what a ridgepole does.
No commonly confused words.