The compound adjective "sweat-stained" is a transparent combination of two Germanic elements. The first element, "sweat," originates from the Old English swāt, which carried the core meanings of perspiration and toil, a concept deeply rooted in the physical experience of labor. The second element, "stained," derives from the Old Norse steina, meaning to paint or color, which entered English and evolved to specifically denote marking with an unwanted color or impurity. When combined, the term literally describes something painted or marked by sweat, creating a vivid descriptor for clothing or objects discolored through physical exertion, directly linking the ancient sense of liquid perspiration to a visible, lasting effect.

Structure: sweat (perspiration) + stained (marked) - sweat: From Old English swāt (perspiration, labor), of Germanic origin; related to Dutch zweet and German Schweiß. Functions as a noun used attributively in this compound. - stained: From Middle English steinen, from Old Norse steina (to paint), of Germanic origin. The past participle form functions as an adjective meaning marked or discolored.