المعنى الاصطلاحي :

The two angels entrusted with questioning each person in his grave after his death by asking him about his Lord, his religion, and his prophet.

الشرح المختصر :

"Munkar wa Nakeer" (Munkar and Nakeer) are two of the angels of Allah, the Exalted. They have blue eyes and black faces. They come to the deceased in his grave and ask him about his Lord, his religion, and his prophet. They were given these names because they come in a form that is "munkarah" (strange, unknown, unfamiliar), which man is not accustomed to, the deceased is not familiar with, and is not pleasant to the lookers. They are also called "Al-Fattānān" (the two testers), because they test people in their graves. The believer is granted the ability to give the right answer, while the disbeliever and the hypocrite give the wrong answer – we seek Allah’s refuge from that. These names were explicitly mentioned in the Hadith of Abu Hurayrah, may Allah be pleased with him, which was transmitted in its complete form by Ibn Hibbān in his Saheeh, and it includes the words: "When the deceased – or when a person – is put in the grave, two black and blue angels come to him. One of them is called Al-Munkar, and the other is called An-Nakeer... "