Lit. “Going forth from one place, and assembling in another.” Hence the word is used in the Qur’an in two senses, viz. An emigration and an assembly, eg Surah lix. 2, “It was He who drove forth from their homes those people of the book (i.e. Jews) who misbelieved, at the first emigration. ” (Hence al-Hashr is the title of the LIXth Surah of the Qur’an) Surah xxvii. 17: “And his hosts of the jinn and men and birds were assembled by Solomon.”
The term Yaumu ‘l-Hashr is therefore used for the Day of Resurrection, or the day when the dead shall migrate from their graves and assemble for judgement. It occurs in this sense in the Qur’an:-
“Verily we cause to live, and we cause to die. To us shall all return.”
“On the day when the earth shall swiftly cleave asunder over the dead, will this gathering be easy to Us.
Based on Hughes, Dictionary of Islam