lazy: [16] Lazy is one of the problem words of English. It suddenly appears in the middle of the 16th century, and gradually replaces the native terms slack, slothful, and idle as the main word for expressing the concept ‘averse to work’, but no one knows for sure where it came from. Early spellings such as laysy led 19th-century etymologists to speculate that it may have been derived from lay, but the more generally accepted theory nowadays is that it was borrowed from Low German. Middle Low German had the similar lasich ‘lazy, loose’, which may go back to an Indo-European form denoting ‘slack’. [lazy etymology, lazy origin, 英语词源]