the word 'sunglasses' is a transparent modern english compound, formed by directly combining two existing english words. the first element, 'sun', originates from old english 'sunne', which has proto-germanic and ultimately proto-indo-european roots referring to the celestial body. the second element, 'glasses', is the plural of 'glass', here referring to lenses, which derives from old english 'glæs', related to a proto-germanic term for the material. the compound's logic is entirely literal, describing protective eyewear designed specifically for use against the glare of the sun, a practical naming convention that emerged with the object's widespread use in the 20th century.

Structure: sun (sun) + glasses (glasses) 'sun' (old english, noun, denoting the celestial body). 'glasses' (english, plural noun, short for 'eyeglasses', denoting lenses set in a frame to aid vision).