Vayu (वायु), Wayu or Hayu (हायु) is a Sino-Tibetan language spoken in Nepal by about 1,520 people in Bagmati Province. Dialects include Pali gau (पालि गाउ) Mudajor Sukajor Ramechhap Sindhuli and Marin Khola.

The Vayu language features SOV ordering. There are strong Nepali influences in its phonology, lexicon, and grammar. Its writing system uses the Devanagari script. There are no known monolingual speakers of the language, as its speaking population also uses Nepali.^[1] Despite a lack of monolingual children, use of Vayu has survived into the 21st century ^[2]

Hayu is spoken in the following locations of Nepal.^[1]

• Ramechhap District, Bagmati Province: Mudajor and Sukajor villages
• Sindhuli District: Manedihi village

Hayu is spoken in the Sunkoshi valley, southwards across the Mahabharat range. Ethnic Hayu live on the hills on both sides of the Sun Kosi River but the language is only spoken in the villages listed.