The Online Maithili Language Thesaurus is a milestone in Maithili Lexicography. In the history of Maithili thesauri, the Varna-Ratnakara by Jyotirishwar Thakur (1290–1350) is the only thesaurus to date which was compiled around 1324 AD (Jha & Madhusudhan, 2024). After this, the Online Maithili Language Thesaurus is the second thesaurus in the history of the Maithili language. But, based on International Standards of thesaurus construction, ISO 25964-1:2011 and Indian Standards IS 16551:2017, the Online Maithili Language Thesaurus is the first in the linguistic history of Maithili.