Keen (Adjective) - तीव्र/उत्सुक
Antonyms:Blunt/Dull/Apathetic.

Keep (Verb) - रखना
Antonyms:Giveup/Discard/Abandon.

Kind (Adjective) - दयालु
Antonyms:Unkind/Mean/Nasty.

Kindly (Adjective) - कृपालु/उपकारी
Antonyms:Unkind/Mean/Disagreeable.

Know (Verb) - जानना
Antonyms:Ignore/Misunderstand.

Knowing (Adjective) - ज्ञान
Antonyms:Ingenuous/Innocent/Accidental.

Knowledge (Noun) - ज्ञान/परिचय
Antonyms:Ignorance/Illiteracy.

Known (Adjective) - जाना हुआ/प्रसिद्ध/परिचित
Antonyms:Unknown/Secret.

Known-how (Noun) - ज्ञात
Antonyms:Inability/Ignorance.