boulder-stonen.

Etymology: Etymology obscure. With Middle English bulderston , compare Swedish dialect (East Gothland) bullersten a large stone in a stream, one which makes a rumbling noise in the water, as opposed to klappersten a smaller pebble; < Swedish buller noise, roar, bullr-a to roar, rumble + sten = stone n. This gives a passable sense; but no corresponding word is known elsewhere in Swedish, Old or New, Icelandic, Norwegian, or Danish; so that actual relation between the northern English and Swedish dialect word cannot be asserted. No words answering to Swedish buller, bullra, exist in Old or New Icelandic; but Danish has bulder ‘tumbling noise’, buldre ‘to racket, rattle, make a noise’. If either these words were in use in northern English, or a compound *buldersteen in Danish, it would be natural to find here the origin of the English word; but no such connecting links are found. The verb and noun seem indeed to exist in the Scots buller ‘to bellow, roar’, buller ‘bellowing, roar, loud gurgling sound’, but this is not quite the shade of sense required, while the form it would yield is not bulder-, bowlder-, bowther-, or boother-, as actually found in North. English dialect, but *bullerstane, which is not found.