noun
native language; local tongue
Refers to the language spoken by the indigenous or local people of a region, often contrasted with a colonial or national language.
その島では今でも土語が話されている。
The native language is still spoken on that island.
noun
Used for a regional dialect or non-standard variety of a language, often with a nuance of being rustic or local.
彼は故郷の土語で話し始めた。
He started speaking in his hometown dialect.
Compound of 土 (do, 'earth, local, indigenous') and 語 (go, 'language'). The exact historical derivation is uncertain, but the word has been used to refer to local or native languages and dialects.