Last Night = اَلْبَارِحَةَ and اَللَيْلَةَ
The word for “last night” in Arabic is اَلْبَارِحَةَ (al-baarihah). Before midday however, when the sun reaches and then passes its zenith, we would refer to the night that has passed as اللَيْلَةَ (al-laylah). So at 10:00am, for example, you would say رَأَيْتُ كَذَا فِي الْمَنَامِ اللَيْلَةَ I saw such and such a thing in my dream last night (al-laylah). After midday, referring to the same dream, you would use the word اَلْبَارِحَةَ rather than اَللَيْلَةَ . The latter word would now refer to the coming night, i.e. tonight. The phrase for the night before last is الْبَارِحَةَ الأَولَى .