A student of Arabic asked on a language-learning discussion board about the difference between أَمْسِ and البارِحَة, if there was any. After all, they both mean “yesterday”. This got me thinking… The word البارحة comes from بَرَحَ, which means “he left/went away”. (If you’re familiar with كان وأخواتها, you might be familiar with this verb in its negative form ما برح, which means “he stayed/continued to be”.) The active participle of برح is بارِح, so a person/thing that has left is referred to as بارح. So how did بارح become البارحة? I did some googling and found out that the term is short for الليلة البارحة, which literally means “the night that has gone”, i.e. last night. Some dialects have extended the usage of this word to include the day that preceded said night, i.e. yesterday, although some dialects have retained its usage as “last night”. Now let’s go back to our question: What’s the difference between أمس and البارحة? Well, أمس means “yesterday” and can’t mean anything else. البارحة is idiomatically used to mean “yesterday”, but it can refer to any feminine thing/person that has gone. For example, you can say, برحت المرأة من مكانها، فهي بارحة In other words, when a woman leaves her place, we can refer to her using the feminine active participle of برح, which is بارحة.