gladyoudaoicibaDictYouDict[glad 词源字典]
glad: [OE] The original meaning of Old English glæd was ‘bright, shining’. It went back to a prehistoric Germanic *glathaz, which was related to Latin glaber ‘smooth, bald’ (source of English glabrous [17] and Old Slavic gladuku ‘smooth’). ‘Happy’ is a secondary semantic development, which evidently took place before the various Germanic dialects went their own way, for it is shared by Swedish and Danish glad (the sense ‘smooth’, also an extension of ‘bright, shining’, is preserved in German glatt).
=> glabrous[glad etymology, glad origin, 英语词源]
glad (adj.)youdaoicibaDictYouDict
Old English glæd "bright, shining, gleaming; joyous; pleasant, gracious" (also as a noun, "joy, gladness"), from Proto-Germanic *glada- (cognates: Old Norse glaðr "smooth, bright, glad," Danish glad "glad, joyful," Old Saxon gladmod, in which the element means "glad," Old Frisian gled "smooth," Dutch glad "slippery," German glatt "smooth"), from PIE *ghel- (2) "to shine," with derivatives referring to bright materials and gold (see glass). The notion is of being radiant with joy; the modern sense "feeling pleasure or satisfaction" is much weakened. Slang glad rags "one's best clothes" first recorded 1902.