IPA: /ˈstrɔːŋ.hoʊld/
KK: /ˈstrɔŋˌhoʊld/
A secure and fortified place, often used as a refuge or a center for a specific group or idea.
The castle served as a stronghold for the knights during the war.
Stronghold → It is formed from "strong" (from Old English "strang", meaning having power or force) and "hold" (from Old English "healdan", meaning to keep or to hold). A stronghold refers to a place that is held strongly or fortified against attack.
Think of a place that is 'held' ('hold') firmly and is 'powerful' ('strong') — that's what a stronghold is.
No commonly confused words.