Recluse
Part of speech: adjective
Definition: (now rare) Sequestered; secluded, isolated. (now rare) Hidden, secret.
Part of speech: noun
Definition: A person who lives in self-imposed isolation or seclusion from the world, especially for religious purposes; a hermit. The place where a recluse dwells; a place of isolation or seclusion. A brown recluse (spider.)
Loner
Part of speech: noun
Definition: One who is alone, lacking or avoiding the company of others.