The word "sunless" is a transparent compound formed within English from its native Germanic elements. The first element, "sun," descends from the Old English sunne, which itself originates from the Proto-Germanic sunnōn, a feminine noun whose ultimate Proto-Indo-European root is sóh₂wl̥, meaning "sun." The suffix "-less" derives from Old English -lēas, meaning "devoid of," originating from the independent adjective lēas (meaning "false, empty") and related to the verb lēosan ("to lose"). The literal, compositional meaning "devoid of the sun" has remained stable from its Old English formation to its modern usage, where it describes both literal physical darkness and, by extension, metaphorical gloom or cheerlessness.

Structure: sun (the star) + less (without) - sun: From Old English sunne, of Germanic origin; related to Dutch zon and German Sonne. Functions as the core noun root. - less: From Old English -lēas, meaning "devoid of, free from". Functions as a suffix forming adjectives.