alone; by oneself; on one's own — doing or being without help or company from others.
子どもが一人で外出するのは心配だ。
I'm worried about a child going out alone.
週末に映画を一人で見に行った。
I went to see a movie by myself on the weekend.
彼は一人で問題を解決した。
He solved the problem on his own.
一人で暮らすのは自由だが時々寂しい。
Living alone is freeing, but sometimes lonely.