In the most common historical sense, 'Syria' refers to the entire northern Levant, including Alexandretta and the ancient city of Antioch or in an extended sense the entire Levant as far south as Roman Egypt, but not including Mesopotamia.
The area of "Greater Syria" (سُوْرِيَّة ٱلْكُبْرَىٰ, Sūrīyah al-Kubrā); also called "Natural Syria" (سُوْرِيَّة ٱلطَّبِيْعِيَّة, Sūrīyah aṭ-Ṭabīʿīyah) or "Northern Land" (بِلَاد ٱلشَّام, Bilād ash-Shām), extends roughly over the medieval Arab Caliphate province of Bilad al-Sham, encompassing the Eastern Mediterranean or the Levant, and Western Mesopotamia.
The Muslim conquest of the Levant in the 7th century gave rise to this province, which encompassed much of the region of Syria, and became largely overlapping with this concept.
Other sources indicate that the term Greater Syria was coined during Ottoman rule, after 1516, to designate the approximate area included in present-day Lebanon, Syria, Jordan, Israel, and Palestine.

The uncertainty in the definition of the extent of "Syria" is aggravated by the etymological confusion of the similar-sounding names Syria and Assyria.
The question of the ultimate etymological identity of the two names remains open today, but regardless of etymology, the two names have often been taken as exchangeable or synonymous from the time of Herodotus.
In the Roman Empire, 'Syria' and 'Assyria' already referred to two separate entities, Roman Syria and Roman Assyria.

Killebrew and Steiner, treating the Levant as the Syrian region, gave the boundaries of the region as such: the Mediterranean Sea to the west, the Arabian Desert and Mesopotamia to the east, and the Taurus Mountains of Anatolia to the north.

For Pliny the Elder and Pomponius Mela, Syria covered the entire Fertile Crescent.
In Late Antiquity, "Syria" meant a region located to the East of the Mediterranean Sea, West of the Euphrates River, North of the Arabian Desert and South of the Taurus Mountains, thereby including modern Syria, Lebanon, Jordan, Israel, the State of Palestine, and parts of Southern Turkey, namely the Hatay Province and the Western half of the Southeastern Anatolia Region.
This late definition is equivalent to the region known in Classical Arabic by the name ash-Shām (ٱلشَّام /ʔaʃ-ʃaːm/, which means the north [country] (from the root šʔm شَأْم "left, north").
After the Islamic conquest of Byzantine Syria in the 7th century, the name Syria fell out of primary use in the region itself, being superseded by the Arabic equivalent Bilād ash-Shām ("Northern Land'"), but survived in its original sense in Byzantine and Western European usage, and in Syriac Christian literature.
In the 19th century the name Syria was revived in its modern Arabic form to denote the whole of Bilad al-Sham, either as Suriyah or the modern form Suriyya, which eventually replaced the Arabic name of Bilad al-Sham.
After World War I, the name 'Syria' was applied to the French Mandate for Syria and the Lebanon, and the contemporaneous but short-lived Arab Kingdom of Syria.
In the most common historical sense, 'Syria' refers to the entire northern Levant, including Alexandretta and the ancient city of Antioch or in an extended sense the entire Levant as far south as Roman Egypt, but not including Mesopotamia. The area of "Greater Syria" (سُوْرِيَّة ٱلْكُبْرَىٰ, Sūrīyah al-Kubrā); also called "Natural Syria" (سُوْرِيَّة ٱلطَّبِيْعِيَّة, Sūrīyah aṭ-Ṭabīʿīyah) or "Northern Land" (بِلَاد ٱلشَّام, Bilād ash-Shām), extends roughly over the medieval Arab Caliphate province of Bilad al-Sham, encompassing the Eastern Mediterranean or the Levant, and Western Mesopotamia. The Muslim conquest of the Levant in the 7th century gave rise to this province, which encompassed much of the region of Syria, and became largely overlapping with this concept. Other sources indicate that the term Greater Syria was coined during Ottoman rule, after 1516, to designate the approximate area included in present-day Lebanon, Syria, Jordan, Israel, and Palestine.
The uncertainty in the definition of the extent of "Syria" is aggravated by the etymological confusion of the similar-sounding names Syria and Assyria. The question of the ultimate etymological identity of the two names remains open today, but regardless of etymology, the two names have often been taken as exchangeable or synonymous from the time of Herodotus. In the Roman Empire, 'Syria' and 'Assyria' already referred to two separate entities, Roman Syria and Roman Assyria.
Killebrew and Steiner, treating the Levant as the Syrian region, gave the boundaries of the region as such: the Mediterranean Sea to the west, the Arabian Desert and Mesopotamia to the east, and the Taurus Mountains of Anatolia to the north.
For Pliny the Elder and Pomponius Mela, Syria covered the entire Fertile Crescent. In Late Antiquity, "Syria" meant a region located to the East of the Mediterranean Sea, West of the Euphrates River, North of the Arabian Desert and South of the Taurus Mountains, thereby including modern Syria, Lebanon, Jordan, Israel, the State of Palestine, and parts of Southern Turkey, namely the Hatay Province and the Western half of the Southeastern Anatolia Region. This late definition is equivalent to the region known in Classical Arabic by the name ash-Shām (ٱلشَّام /ʔaʃ-ʃaːm/, which means the north [country] (from the root šʔm شَأْم "left, north"). After the Islamic conquest of Byzantine Syria in the 7th century, the name Syria fell out of primary use in the region itself, being superseded by the Arabic equivalent Bilād ash-Shām ("Northern Land'"), but survived in its original sense in Byzantine and Western European usage, and in Syriac Christian literature. In the 19th century the name Syria was revived in its modern Arabic form to denote the whole of Bilad al-Sham, either as Suriyah or the modern form Suriyya, which eventually replaced the Arabic name of Bilad al-Sham. After World War I, the name 'Syria' was applied to the French Mandate for Syria and the Lebanon, and the contemporaneous but short-lived Arab Kingdom of Syria.
Syria (region)