Looking up...
alone; by oneself; without any companions or assistance
単独で旅行するのは楽しいが、時には孤独を感じる
Traveling alone is fun, but sometimes you feel lonely.
Often used to describe someone acting independently or without support.
Often used to describe someone working or traveling alone.
From '単' (single) + '独' (alone), combining to mean 'alone' or 'by oneself'.
Can be used in both positive and negative contexts, depending on the situation.