Imperial Aramaic is a linguistic term, coined by modern scholars in order to designate a specific historical variety of Aramaic language. The term is polysemic, with two distinctive meanings, wider (sociolinguistic) and narrower (dialectological). Since most surviving examples of the language have been found in Egypt, the language is also referred to as Egyptian Aramaic.

Some scholars use the term as a designation for a distinctive, socially prominent phase in the history of Aramaic language, that lasted from the middle of the 8th century BCE to the end of the 4th century BCE and was marked by the use of Aramaic as a language of public life and administration in the late Neo-Assyrian Empire and its successor states, the Neo-Babylonian Empire and the Achaemenid Empire, also adding to that some later (Post-Imperial) uses that persisted throughout the early Hellenistic period. Other scholars use the term Imperial Aramaic in a narrower sense, reduced only to the Achaemenid period, basing that reduction on several strictly linguistic distinctions between the previous (Neo-Assyrian and Neo-Babylonian) phase and later (more prominent) Achaemenid phase.

Since all of those phases can be semantically labelled as "imperial", some scholars opt for the use of more specific and unambiguous terms, like Neo-Assyrian Aramaic and Neo-Babylonian Aramaic (for the older phases), and Achaemenid Aramaic (for the later phase), thus avoiding the use of the polysemic "imperial" label, and its primarily sociolinguistic implications. Similar issues have arisen in relation to the uses of some alternative terms, like Official Aramaic or Standard Aramaic, that were also criticized as unspecific. All of those terms continue to be used differently by scholars.

The Elephantine papyri and ostraca, as well as other Egyptian texts, are the largest group of extant records in the language, collected in the standard Textbook of Aramaic Documents from Ancient Egypt. Outside of Egypt, most texts are known from stone or pottery inscriptions spread across a wide geographic area. More recently a group of leather and wooden documents were found in Bactria, known as the Bactria Aramaic documents.

The term "Imperial Aramaic" was first coined by Josef Markwart in 1927, calling the language by the German name Reichsaramäisch. In 1955, Richard N. Frye noted that no extant edict expressly or ambiguously accorded the status of "official language" to any particular language, causing him to question the classification of Imperial Aramaic. Frye went on to reclassify Imperial Aramaic as the lingua franca used in the territories of the Achaemenid Empire, further suggesting that the language's use was more prevalent in these areas than initially thought.

The native speakers of Aramaic, the Arameans, settled in great numbers in Babylonia and Upper Mesopotamia during the ages of the Neo-Assyrian and Neo-Babylonian Empires. The massive influx of settlers led to the adoption of Aramaic as the lingua franca of the Neo-Assyrian Empire. After the Achaemenid conquest of Mesopotamia in 539 BC, the Achaemenids continued the use of Aramaic as the language of the region, further extending its prevalence by making it the imperial standard (thus "Imperial" Aramaic) so it may be the "vehicle for written communication between the different regions of the vast empire with its different peoples and languages." The adoption of a single official language for the various regions of the empire has been cited as a reason for the at the time unprecedented success of the Achaemenids in maintaining the expanse of their empire for a period of centuries.

One of the most extensive collections of texts written in Imperial Aramaic is the Fortification Tablets of Persepolis, of which there are about five hundred. Other extant examples of Imperial Aramaic come from Egypt, such as the Elephantine papyri. Egyptian examples also include the Words of Ahikar, a piece of wisdom literature reminiscent of the Book of Proverbs. Scholarly consensus regards the portions of the Book of Daniel (i.e., 2:4b-7:28) written in Aramaic as an example of Imperial Aramaic. In November 2006, an analysis was published of thirty newly discovered Aramaic documents from Bactria which now constitute the Khalili Collection of Aramaic Documents. The leather parchment contains texts written in Imperial Aramaic, reflecting the use of the language for Achaemenid administrative purposes during the fourth century in regions such as Bactria and Sogdia.

The evolution of alphabets from the Mediterranean region is commonly split into two major divisions: the Phoenician-derived alphabets of the West, including the Mediterranean region (Anatolia, Greece, and the Italian peninsula), and the Aramaic-derived alphabets of the East, including the Levant, Persia, Central Asia, and the Indian subcontinent. The former Phoenician-derived alphabets arose around the 8th century BC, and the latter Aramaic-derived alphabets evolved from the Imperial Aramaic script around the 6th century BC. After the fall of the Achaemenid Empire, the unity of the Imperial Aramaic script was lost, diversifying into a number of descendant cursives. Aramaic script and, as ideograms, Aramaic vocabulary would survive as the essential characteristics of the Pahlavi scripts, itself developing from the Manichaean alphabet.