Old English idelnes "frivolity, vanity, emptiness; vain existence;" see idle (adj.) + -ness. Old English expressed the idea we attach to in vain by in idelnisse. In late Old English it began to acquire its sense of "state of being unoccupied, doing no work, or indolent." Similar formation in Old Saxon idilnusse, Old Frisian idlenisse, Old High German italnissa. Spenser, Scott, and others use idlesse to mean "condition of being idle" in a positive sense, as a pleasure.