Abau is a Papuan language spoken in southern Sandaun Province of Papua New Guinea, primarily along the border with Indonesia.

In 2002, there were estimated to be between 4,500 and 5,000 speakers, and this number does not appear to have declined since the first accurate count in the 1970s.

Abau is reported to have whistled speech.

Abau has the simplest phonemic inventory in the Sepik language family.^[2]

Pronouns are:^[3]

The dual and plural numbers only distinguish between first person and non-first person. Also, the third-person gender distinction exists only for the singular, but not the dual or plural forms.

Abau noun classes are:^[3]

Nouns can take on different class affixes depending on the physical characteristics being emphasized. Examples:^[3]

su ‘coconut’

• su pi-ron /coconut class.5-one/ ‘a coconut palm’
• su ka-mon /coconut class.2-one/ ‘a coconut’

pey ‘sugarcane’

• pey pi-ron /sugarcane class.5-one/ ‘one stalk of uncut sugarcane’
• pey houk-mon /sugarcane class.12-one/ ‘one piece of sugarcane’
• pey eind-mon /sugarcane class.9-one/ ‘bundle of stored stalks of sugarcane’
• pey hnaw-mon /sugarcane class.11-one/ ‘one bundle of sugarcane ready for transport’

Like most other Sepik languages, Abau overtly marks grammatical gender (see Sepik languages#Gender). The same object can be classified as either masculine or feminine, depending on the physical characteristics intended for emphasis. Example:^[3]

youk ‘paddle’

• youk se ‘paddle M.DAT’ (focuses on the length of the paddle)
• youk ke ‘paddle F.DAT’ (focuses on the flat nature of the two-dimensional paddle blade)

The following basic vocabulary words are from Foley (2005)^[4] and Laycock (1968),^[5] as cited in the Trans-New Guinea database:^[6]