aloof

Synonyms: above apart casual chilly cold cold fish cool detached distant forbidding hard-boiled hard-hearted haughty incurious indifferent laid back loner lone wolf offish on ice putting on airs reserved secluded solitary standoffish stuck up supercilious thick-skinned unapproachable unconcerned unfriendly uninterested unresponsive unsociable unsympathetic uppity withdrawn

Antonyms: concerned friendly sociable