late 14c., "stray blindly or blunderingly, wander aimlessly, go astray;" c. 1400, of persons, "shout loudly and angrily," from a Low German source, such as Middle Low German blüstren "to blow violently," East Frisian blüstern "to bluster," probably from the same source as blow (v.1), or perhaps imitative. Of weather in English from mid-15c. Related: Blustered; blustering.