Mortlockese (Kapsen Mwoshulók), also known as Mortlock or Nomoi, is a language that belongs to the Chuukic group of Micronesian languages in the Federated States of Micronesia spoken primarily in the Mortlock Islands (Nomoi or Lower Mortlock Islands and the Upper Mortlock Islands). It is nearly intelligible with Satawalese, with an 18 percent intelligibility and an 82 percent lexical similarity, and Puluwatese, with a 75 percent intelligibility and an 83 percent lexical similarity. The language today has become mutually intelligible with Chuukese, though marked with a distinct Mortlockese accent. Linguistic patterns show that Mortlockese is converging with Chuukese since Mortlockese now has an 80 to 85 percent lexical similarity.
There are approximately five to seven thousand speakers of Mortlockese in the Mortlock Islands, Guam, Hawaii, and the United States. There are at least eleven different dialects that show some sort of correspondence to the Mortlock Island groups.