The Greek historian Arrian in his Anabasis Alexandri (mid-2nd century CE) mentions the existence of a peculiar indigenous language in the city of Side.

[2] In 1964 a large stone block was unearthed near the east gate of Side, with two longer Sidetic texts, including loan words from Greek (istratag from στρατηγός, 'commander' and anathema- from ἀνάθημα, 'votive offering').

In addition, it is believed that some incomprehensible characters in the third book of Hippocrates' Epidemics were originally quotations of the doctor Mnemon of Side, which might have been in the Sidetic script.

It has been argued that there were also Anatolian pronouns (ev, 'this'; ab, 'he/she/it'), conjunctions (ak and za, 'and'), prepositions (de, 'for'), and adverbs (osod, 'there').

A promising candidate is ozad, 'he offered', dedicated' (twice attested with object anathemataz, 'sacrifices'), a 3rd person singular preterite with the common Anatolian ending -d. Like the neighbouring Pamphylian language, aphaeresis is frequent in names in Sidetic (e.g. Poloniw for Apollonios, Thandor for Athenodoros), as is syncope (e.g. Artmon for Artemon).