المعنى الاصطلاحي :

The ninth day of Dhul-Hijjah.

الشرح المختصر :

"Yawm ‘Arafah" (the Day of ‘Arafah) was called thus because the pilgrims stand and get acquainted above the [mountain] of ‘Arafah. Another opinion suggests that it was called so because the angel Jibreel "‘arrafa" (taught) Ibrāhim (Abraham) how to make Hajj. Another suggests that it is the day of doing "ma‘roof" (good) to the pilgrims. Moreover, it was said that Allah bestows His forgiveness and generosity upon them. In other words, Allah, the Exalted, makes them feel good and gives them the glad tidings of entering Paradise, as Allah mentions in the Qur’an: {And admit them to Paradise, which He has made known to them.} [Muhammad: 6] The Muslims agreed unanimously that standing in ‘Arafah is one of the pillars of Hajj. Whoever abandons it or delays it from its designated time, then his Hajj will be incomplete, he will only be able to make "ihlāl" (lifting the restrictions of "ihrām") by performing ‘Umrah, and he will have to perform Hajj the following year.