I’d always assumed that the Spanish city of Tarifa at the country’s southernmost tip, right next to Gibraltar, was the source of the word tariff, because it was where the Moors collected duties during Spain’s Arabic millennium, however the city was named after its main purpose.
The word tariff originates from the Arabic ta‘rīf (تعريف), meaning “to notify,” “announce,” or “make known”. Rooted in the verb ‘arafa (“to know”), it originally referred to a list of charges, spreading through Mediterranean trade routes in the 16th century via Italian (tariffa) and Spanish (tarifa).
The word was adopted to describe the notification of duties at ports, maintaining its core meaning of “making known” what charges apply to goods. From there, it evolved into the specific economic term for taxes on imported goods.