IPA: /ˈʌndəˌkləʊðɪŋ/
KK: /ˈʌndərˌkloʊðɪŋ/
Clothing worn under outer clothes, typically next to the skin, such as underwear or undergarments.
She bought new underclothing for the summer.
Underclothing → It is formed from "under" (from Old English "under", meaning beneath or below) and "clothing" (from Old English "clāþ", meaning garment or cloth). The word refers to garments worn beneath outer clothing.
Think of something that is worn 'beneath' ('under') the outer garments — that's what underclothing means.
No commonly confused words.