Antisocial
Part of speech: adjective
Definition: Unwilling or unable to associate normally with other people antagonistic, hostile, or unfriendly toward others; menacing Opposed to social order or the principles of society
Example sentence: I suppose being a bit of an antisocial weirdo definitely honed my skills as a soloist. It gave me a lot more opportunities to solo lots of easy routes, which in turn broadened my comfort zone quite a bit and has allowed me to climb the harder things without a rope that I've done now.
Unsociable
Part of speech: adjective
Definition: not needing the company of othersnot congenial or compatibleunfriendly