As salamu ‘alaykum,
The Sura ul Hujuraat 49 of the Qur’an was named after the 4th verse of the Qur’an where it states:
((As for) those who call out to you from behind the private chambers, surely most of them do not understand).
Hujurat is the plural of hujrah, which basically means ‘room’ in English. This chapter of the Qur’an was revealed to Prophet Muhammad in the 8th AH (al Hijrah).
Surat ul Hujurat is a guide to the morals and the code of ethics for Muslims, which forms the fundamental common agreement necessary between any grouping if there is to progress. For example verse 9:
“And if two parties of the believers quarrel, make peace between them; but if one of them acts wrongfully towards the other, fight that which acts wrongfully until it returns to Allah’s command; then if it returns, make peace between them with justice and act equitably; surely Allah loves those who act equitably”.
The word hajrun means stone, to prohibit, to stop, to protect etc, and the word hijaratun means a room. In view of this hijaratun could mean a porous rock which serves as a container for water.
N.B.: If anyone can provide a more accurate meaning, please do not hesitate to let us know.