Brajabuli a dialect and poetic language popularised by vidyapati (14th century), a poet of Mithila. Vidyapati's language was Maithali but he used Brajabuli, a mixture of Maithali and Bangla, to write verses on the dalliance of radha and krishna. This language was called Brajabuli, the language of Braja, because it was spoken extensively in Brajadham and because the verses depict the dalliance of Radha and Krishna in Brajadham. Though the trend to write poetry in Brajabuli began with Vidyapati, it was further developed by the Bengali poets of the later period. The dialect is extinct now.

Vidyapati's verses were very popular in Bengal, so other poets emulated Vidyapati's language and style to write verses on Radha and Krishna. This trend continued till the 19th century. Brajabuli was also used in assam and Orissa. Yashoraj Khan, Shankardev and Ramananda Roy were 16th century poets from Bengal, Assam, and Orissa who wrote in Brajabuli. Perhaps the best Bengali writer of Brajabuli was govindadas kaviraj (16-17th century).

A large number of tatsama and ardha tatsama were common in Brajabuli. Some variations of words in Brajabuli are: মাস (masa, month) > মাহ (maha, month), লাবণ্য (lavanya, sweetness)> লাবনি (lavani, sweetness), দুস্তর (dustara, difficult to cross) > দুতর (dutara, difficult to cross), দৃষ্টি (drsti, sight)> দিঠি (dithi, sight), মেঘ (megha, cloud) > মেহ (meha, cloud), etc. Brajabuli verses are melodious, as the following lines composed about a storm reveal:

‘গগনে অব ঘন মেহ দারুণ (gagane aba ghana' meha daruna)

সঘনে দামিনী চমকই।

(saghane damini chamakai)

কুলিশ পাতন শবদ ঝন ঝন

(kulixa patana' xabada jhana jhana)

পবন খরতর বলসই॥’ (pavana kharatara balasai)

[The sky is overcast with thick clouds; thunder roars, lightning strikes, the rain pours, the wind blows]. [Abul Kalam Manjoor Morshed]