| Thēthi | |
| Nativename: | Thethi Maithili |
| States: | India, Nepal |
| Region: | Mithila |
| Ethnicity: | Maithils |
| Familycolor: | Indo-European |
| Fam2: | Indo-Iranian |
| Fam3: | Indo-Aryan |
| Fam4: | Eastern |
| Fam5: | Bihari |
| Fam6: | Maithili |
| Glotto: | tati1242 |
| Glottoname: | Tati (Maithili) |
Thēthi, also known as Thēth, Thethiya, Thenthi, or Thati, is a Maithili dialect, mainly spoken in the Mithila region of India and Nepal.[1] It is spoken mainly in Kosi, Purnia and Munger divisions of Bihar, India and in some of the adjoining districts of Nepal.[2] It has speakers in India according to the 2011 census.[3]