a.

1. 粗心的，疏忽的；草率的
   He made a careless mistake.

   他犯了一個粗枝大葉的錯誤。

2. 隨便的；自然的
   He sat into a chair with careless ease.

   他隨便往椅子裡舒舒服服一坐。

3. 漫不經心的；淡漠的[（+of/about）]
   She's careless about her clothes.

   她對穿著一點都不講究。

4. 無憂無慮的
   careless days

   無憂無慮的日子

adj.

1. not giving sufficient attention or thought to avoiding harm or mistakes.
2. (careless of/about) not concerned or worried about.
   ▸showing no interest or effort; casual.