Casual; not formal or dressy. Describes clothing, atmosphere, or behavior that is relaxed and informal.
面接以外はカジュアルな服装で構いません。
Other than the interview, casual attire is fine.
あの店はカジュアルな雰囲気で、一人でも入りやすい。
That shop has a casual atmosphere and it's easy to go in alone.
週末はフォーマルではなくカジュアルな集まりにしたい。
I want this weekend's gathering to be casual rather than formal.