royal-blue

The compound adjective 'royal-blue' is a relatively modern formation, emerging in the 19th century to describe a specific, rich shade of blue. The first element, 'royal', draws on its long-standing association with monarchy, prestige, and high status, borrowed into English via Norman French from Latin 'regalis'. The second element, 'blue', has ancient Germanic roots, entering English through Old French. The logic of the compound is straightforward: it uses the connotation of regal opulence and excellence to specify a particularly deep and vivid hue of the primary color blue, implying it is a color fit for royalty or of superior quality.

Structure: royal (regal) + blue (color) 'Royal' originates from Old French 'roial', from Latin 'regalis' (of a king), with the functional role of a modifier indicating quality or association. 'Blue' originates from Old French 'bleu', of Germanic origin, with the functional role of the base noun denoting the color.