An Etymological Dictionary of the German Language/leer
leer, adj., from the equiv. MidHG. lœ̂re, OHG. and OSax. lâri, ‘empty, void’; comp. AS. lœre, gelœ̂re, MidE. ilêre, E. dial. leer, ‘empty, with an empty stomach, hungry.’ It can hardly be determined whether the r represents by rhotacism an earlier s. Perhaps Goth. lasiws, ‘powerless, weak,’ AS. lęswe, ‘weak’ (MidHG. erlęswen, ‘to grow weak’), as well as OIc. lasenn, ‘demolished,’ are the nearest cognates of leer.
leer, if derived from Teut. lêya, may be connected with OIr. lia, 'hunger.'