The Lemnian language was spoken on the island of Lemnos, Greece, in the second half of the 6th century BC. It is mainly attested by an inscription found on a funerary stele, termed the Lemnos stele, discovered in 1885 near Kaminia. Fragments of inscriptions on local pottery show that it was spoken there by a community. In 2009, a newly discovered inscription was reported from the site of Hephaistia, the principal ancient city of Lemnos. Lemnian is largely accepted as being a Tyrsenian language, and as such related to Etruscan and Raetic. After the Athenians conquered the island in the latter half of the 6th century BC, Lemnian was replaced by Attic Greek.
The Lemnian inscriptions are in Western Greek alphabet, also called "red alphabet". The red type is found in most parts of central and northern mainland Greece (Thessaly, Boeotia and most of the Peloponnese), as well as the island of Euboea, and in colonies associated with these places, including most colonies in Italy. The alphabet used for Lemnian inscriptions is similar to an archaic variant used to write the Etruscan language in southern Etruria.
A relationship between Lemnian, Raetic and Etruscan, as a Tyrsenian language family, has been proposed by German linguist Helmut Rix due to close connections in vocabulary and grammar. For example,
Both Etruscan and Lemnian share two unique dative cases, type-I *-si and type-II *-ale, shown both on the Lemnos Stele (Hulaie-ši, 'for Hulaie', Φukiasi-ale, 'for the Phocaean') and in inscriptions written in Etruscan (aule-si, 'to Aule', on the Cippus Perusinus; as well as the inscription mi mulu Laris-ale Velχaina-si, meaning 'I was blessed for Laris Velchaina');
A few lexical correspondences have been noted, such as Lemnian avis ('year') and Etruscan avils (genitive case); or Lemnian šialχvis ('sixty') and Etruscan šealχls (genitive case), both sharing the same internal structure "number + decade suffix + inflectional ending" (Lemnian: ši + alχvi + -s, Etruscan: še + alχl + s);
They also share the genitive in *-s and a simple past tense in *-a-i (Etruscan - as in ame 'was' (< *amai); Lemnian - as in šivai, meaning 'lived').