unsociable

The word "unsociable" usually describes a person who does not enjoy being with other people very much, or who does not naturally seek out company. It suggests a preference for solitude and a tendency to stay away from social activities. Imagine an old scholar, deep in books and research. They may be perfectly pleasant when spoken to, yet still avoid parties, small talk, or crowded gatherings. That is the clearest use of the word.

It is important to distinguish "unsociable" from "shy" and "antisocial." A shy person may want company but feel afraid or uneasy in social situations. An unsociable person usually just does not want much company in the first place. "Antisocial" is stronger still, often suggesting harmful or hostile behavior toward others, which is very different from simply preferring quiet evenings alone.

This quality can come from personality, habit, past experience, or present circumstances. Someone may naturally like a quiet life, or they may become more unsociable after loss, stress, illness, or disappointment. It is not always a bad thing. Many people need long stretches of time alone to think, work, or recover. Still, if it becomes extreme and leads to painful isolation, it can be a problem rather than a simple preference.

There is also another common use, especially in British English: "unsociable" can describe times that make normal social life difficult, as in "unsociable hours." In that phrase, it means very early, very late, or otherwise inconvenient times for work or activity. So the word can describe both a person who prefers little company and a schedule that clashes with ordinary social life.

You might describe a character in a novel as "unsociable" to show that they keep to themselves. You could also say, "After his wife's death, he became increasingly unsociable," or "She has to work unsociable hours at the hospital." The key idea is separation from ordinary social contact, whether that comes from a person's habits or from the timing of daily life.