glad (adj.) Look up glad at Dictionary.com
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.