An Etymological Dictionary of the German Language/selten
selten, adj. and adv., ‘rare, rarely,’ from MidHG. sëlten, OHG. sëltan, adv., ‘rarely’; corresponding to the equiv. AS. sëldan, adv., E. seldom, OIc. sjaldan, OFris. sielden, adv. The corresponding adj. is OHG. sëltsâni, MidHG. sëltsœne (AS. sëld-sêne), ‘rare, strange,’ the suffix of which has been supplanted in ModHG. by the more familiar -sam. In Goth. sildaleiks, ‘wonderful,’ to which is allied Goth. sildaleikjan, ‘to be astonished’ (akin to AS. syllîč, E. silly). Cognate terms in the non-Teut. languages are wanting.