An Etymological Dictionary of the German Language/stark
stark, adj., ‘strong,’ from MidHG. starc (and starch), OHG. starc (and starah), adj., ‘strong, vigorous, big’; corresponding to OSax. stark, Du. sterk, AS. stearc, E. stark, OIc. sterkr. To the same Teut. root stark belong by a different gradation Goth. gastaúrknan, ‘to become parched, wither away,’ OIc. storkna, ‘to curdle,’ OHG. storchanên, ‘to become fixed, hard’; hence perhaps ‘fixed’ is the primit. meaning of the root. Lith. strėgti, ‘to stiffen, become numb,’ and ModPers. suturg (base *stṛga), ‘strong,’ are primit. allied. Deriv. ModHG. Stärke, f., ‘starch’ (note the E. word).