IPA: //ˈnaɪtɡaʊn//
KK: /ˈnaɪtˌɡaʊn/
A loose piece of clothing that women and girls wear to sleep in.
She put on her nightgown before going to bed.
Nightgown → It is formed from "night" (from Old English *niht*, meaning the period of darkness) and "gown" (from Old French *goune*, meaning a long dress or garment). A nightgown is a garment worn during the night, typically for sleeping.
Think of the time of 'darkness' ('night') when you wear a 'long dress' ('gown') to sleep. This helps you remember that a nightgown is a dress worn at night.
No commonly confused words.