The first mention of the town is in Akkadian Rēš ina during the reign of the Assyrian king Adad-nirari II (911-891 BC).
The Arabic name Ras al-Ayn derives from the Akkadian and has the same meaning; "head of the spring", or idiomatically, "hill of the spring", indicating a prominent mountain formation close to a well.

The ancient Greek geographer Ptolemy (d. 168) names the town Raisena.
The town, as part of the Roman Empire, was called Ressaina/Resaina.
Another name was Theodosiopolis, after emperor Theodosius I, who enlarged the town in 380.
The 11th century Arab geographer Muhammad al-Idrisi visited the town, mentioning its name as Ras al-'Ayn, and assigning it to Diyar Rabi'a (abode of the Arab tribe Rabi'a).
He also described it as a big city with plenty of water, around 300 springs from which most of al-Khabur river starts.
 In addition to Ras al-Ayn, medieval Arab Muslim sources refer to the town sometimes as Ain Werda.
Nineteenth-century English sources refer to the town as Ras Ain, Ain Verdeh (1819), or Ras el Ain (1868).
The Kurdish name Serê Kaniyê also means "head of the spring" or "head of the fountain", referring to water source areas.
This name is probably a modern literal translation of the ancient Semitic name.
The first mention of the town is in Akkadian Rēš ina during the reign of the Assyrian king Adad-nirari II (911-891 BC). The Arabic name Ras al-Ayn derives from the Akkadian and has the same meaning; "head of the spring", or idiomatically, "hill of the spring", indicating a prominent mountain formation close to a well.
The ancient Greek geographer Ptolemy (d. 168) names the town Raisena. The town, as part of the Roman Empire, was called Ressaina/Resaina. Another name was Theodosiopolis, after emperor Theodosius I, who enlarged the town in 380. The 11th century Arab geographer Muhammad al-Idrisi visited the town, mentioning its name as Ras al-'Ayn, and assigning it to Diyar Rabi'a (abode of the Arab tribe Rabi'a). He also described it as a big city with plenty of water, around 300 springs from which most of al-Khabur river starts.  In addition to Ras al-Ayn, medieval Arab Muslim sources refer to the town sometimes as Ain Werda. Nineteenth-century English sources refer to the town as Ras Ain, Ain Verdeh (1819), or Ras el Ain (1868). The Kurdish name Serê Kaniyê also means "head of the spring" or "head of the fountain", referring to water source areas. This name is probably a modern literal translation of the ancient Semitic name.
Ras al-Ayn