An Etymological Dictionary of the German Language/schlaff

by Friedrich Kluge

schlaff, adj., ‘relaxed, loose, indolent,’ from MidHG. and OHG. slaf (gen. slaffes), ‘relaxed, idle, impotent’; comp. LG. and Du. slap, ‘relaxed, impotent,’ whence ModHG. schlapp, retaining the LG. p, is borrowed. Goth. *slapa- is perhaps a graded form of the root slép, as lata-, ‘idle, lazy,’ is of the root lêt, ‘to omit’ (see laß). OSlov. slabŭ, ‘relaxed, weak,’ and Lat. lâbi, ‘to glide,’ lăbare, ‘to totter,’ have been rightly compared with the prim. Teut. slapa-, ‘relaxed.’ See schlafen.