IPA: /ˈɪntəˌlaɪnɪŋ/
KK: /ˈɪntərˌlaɪnɪŋ/
A layer of material placed between the outer fabric and the inner lining of a garment to provide additional support, warmth, or structure.
The tailor used a soft interlining to give the coat a more polished look.
Interlining → It is formed from "inter-" (meaning between) and "lining" (from Old English "lin" meaning linen or cloth). The word refers to a layer of material placed between two layers of fabric, thus existing between them.
Think of something that goes 'between' ('inter-') two layers of fabric ('lining') — that's what interlining is.