IPA: /ɪnˈdɔrz/
KK: /ɪnˈdɔrz/
In or into a house or building.
We decided to stay indoors during the storm.
Indoors is formed from "in-" (meaning within) and "doors" (from Old English "duru", meaning a barrier or entrance). The word "indoors" refers to being within the barriers or confines of a building, specifically inside through the doors.
Think of being 'within' ('in-') the 'doors' of a building — that's what it means to be indoors.
No commonly confused words.