Hail-fellow-well-met is an idiom used to describe someone who is overly friendly and sociable, often in a superficial way. The antonyms for this term can be unfriendly, reserved, aloof, distant, or cold. Someone who is unfriendly is not amiable or approachable, while being reserved means being cautious or formal in behavior, and being aloof means being distant or detached from others. People who are cold, on the other hand, are indifferent or unfeeling towards others, and lack warmth or kindness. These antonyms indicate a negative behavior that is the opposite of the friendly and outgoing nature of a hail-fellow-well-met person.