The antonym of 'Diligent' is-

The Antonym of diligent is- ক) indolent.
Indolent (adj)- অলস; পরিশ্রমবিমুখ।

• Diligent (adj)-
- English Meaning: Characterized by steady, earnest, and energetic effort.
- Bangla Meaning: অধ্যবসায়ী।

• Example sentences:
- She is very diligent in her studies.
- Diligent workers achieve success.

• Other options:
Garrulous (adj)- বাচাল।
Industrious (adj)- পরিশ্রমী।

Source:
English & Bangla Online Dictionary & Grammar.