Usku, or Afra, is a nearly extinct and poorly documented Papuan language spoken by 20 or more people, mostly adults, in Usku village, Senggi District, Keerom Regency, Papua, Indonesia.

Wurm (1975) placed it as an independent branch of Trans–New Guinea, but Ross (2005) could not find enough evidence to classify it. Usher (2020) found that it was one of the West Pauwasi languages, though divergent from the other two branches of that family. Foley (2018) classifies Usku as a language isolate.

An automated computational analysis (ASJP 4) by Müller et al. (2013) found lexical similarities between Usku and Kaure. However, since the analysis was automatically generated, the grouping could be either due to mutual lexical borrowing or genetic inheritance.

Basic vocabulary of Usku from Im (2006), quoted by Foley (2018):

The following basic vocabulary words are from the Trans-New Guinea database:

Usku morphology as inferred by Foley (2018):

Word order in Usku is SOV.

Some of the few documented sentences in Usku are: