The term "stained-glass" is a compound adjective formed from the past participle "stained" and the noun "glass." The word "stained" in this context originates from a Scandinavian root meaning to paint or colour, reflecting the artistic process of applying metallic pigments to glass before firing. "Glass" has ancient Germanic origins, referring to the material itself. The compound emerged in the late 18th century to specifically describe the iconic coloured windows of Gothic cathedrals, where the "staining" process created permanent, luminous images. Thus, the term literally means "glass that has been coloured," directly linking the artistic technique to the finished architectural element.

Structure: stained (sense) + glass (sense) - stained: From Middle English 'steynen', from Old Norse 'steina' (to paint). In this compound, it functions as a past participle meaning "coloured or marked with a pigment." - glass: From Old English 'glæs', from Proto-Germanic 'glasą'. It functions as the head noun, denoting the hard, brittle, transparent substance.