recluse
/ˈre-ˌklüs/
adjective
marked by withdrawal from society : solitary
noun
a person who leads a secluded or solitary life
noun
a venomous spider (Loxosceles reclusa) especially of the southern and central U.S. that has a violin-shaped mark on the cephalothorax and produces a dangerous cytotoxin which can cause necrotic lesions