Biloxi is a dormant Siouan language once spoken along the Gulf of Mexico in the Southeastern United States. Biloxis merged with the unrelated Tunicas in 1981 to form the Tunica-Biloxi Tribe of Louisiana. This is a newly enhanced and expanded Third Edition of the revised Biloxi-English Dictionary originally published in 2011, with a Second Edition in 2015, incorporating the language notes of the linguists Albert Gatschet, James Owen Dorsey, John Swanton, Mary Haas, and Morris Swadesh. The dictionary contains over 2,100 entries with etymological analyses and notations, an English-Biloxi index, comparative data from Siouan and other languages, cross-referencing of entries as well as appendices on numbers, days of the week, flora and fauna, place names, and medicinal plants. For this edition, new entries are included that did not appear in the first two editions, along with new notes reflecting the latest research. In addition, 74 more example phrases and sentences have been added. The Biloxi-English Dictionary serves as a handy reference for Biloxi descendants who want to learn their ancestral language as well as serving as a valuable research tool for linguists, anthropologists, historians, and others interested in Biloxi and Siouan languages in general.