noun
also brown recluse
Etymology: recluse probably from New Latin reclusa , specific epithet, from Late Latin, feminine of reclusus shut up; from its living chiefly in dark corners — more at recluse
: a venomous spider of the genus Loxosceles ( L. reclusa ) introduced especially into the southern and central United States that has a violin-shaped mark on the cephalothorax and produces a dangerous cytotoxin which can cause necrotic lesions