Learn Farsi: مراجعین گرامی، لطفاً از تجمع کردن خودداری کنید. - Dear clients, please refrain from gathering.

The word morâje'in (مراجعین) is the plural of the Arabic loanword morâje' (client or visitor). In formal Farsi, Arabic words referring to people often take the Arabic animate plural suffix -in (ـین). You cannot use this suffix on native Farsi words; it is strictly for Arabic loanwords.

Could I just use the standard Farsi plural and say morâje'hâ instead of morâje'in?

Grammatically, yes. You can use the standard Farsi plural suffix -hâ (ها) for almost anything. However, morâje'in sounds much more formal and administrative, which perfectly matches the polite, official tone of this public announcement.

Why use gerâmi for 'dear' here instead of the more common word aziz?

While aziz (عزیز) means 'dear' in an affectionate or personal way, gerâmi (گرامی) translates closer to 'esteemed' or 'honored'. It is the standard, professional word used to address customers, clients, or audiences in formal Farsi.

Why is the preposition az placed right before tajammo' kardan (gathering)?

The preposition az (از) is required by the verb at the end of the sentence, khoddâri kardan (خودداری کردن), which means 'to refrain'. Just like in English where we refrain 'from' doing something, Farsi requires az before the action you are avoiding.