Lakotaca ya da Lakota Siyucası (kendilerince Lakȟótiyapi; İngilizce Lakota, Lakhota, Lakota Sioux, Teton, Teton Sioux), ABD'de daha çok Kuzey ve Güney Dakota eyaletlerinde, daha az olarak kuzey Nebraska, güney Minnesota ve kuzey Montana eyaletlerinde ve Kanada'da LakotaSiyuları tarafından konuşulan Siyucanın bir lehçesidir. Konuşanı 1997 yılındaki rakamlara göre 6.200  kişidir.
İNGİLİZCE ÇEVİRİSİ : Native languages in the United States are in the throes of a prolonged and deadly crisis. For the past 400 years, Native Peoples and their languages have been steadily and undeniably disappearing. Though the historical fate of Native Peoples has been reluctantly acknowledged, less is publicly known about the associated fate of their languages. In recent years, this expanding crisis has reached a deadly climax. Of the many hundreds of languages spoken in North America before the arrival of Euro-American colonizers, only a handful, perhaps a dozen, can be considered viable enough today to survive. Lakota is unique from languages like English because of the intimate way it is tied to the pre-reservation world. This world was closely associated with living in small groups, living close to nature, traveling a good deal across large areas, and having a rich spiritual life. Lakota cultural attributes are reflected in the language. For example, Lakota is rich in ways to describe the many subtle aspects of social behavior revolving around areas of feigning interest, pouting, courting, and many others. Moreover, in Lakota, nature is used as the primary source for the metaphor models. Physical appearance is often tied to nature, for example, someone could be "Skinny as a crane," or "Ragged as a turtle." Lakota is also very good at emphasizing the finer attributes of travel. A person can be considered to be coming or going to or from specific places in many levels detail. Lakota greetings themselves reflect this tendency, wherein English "welcome" is literally Lakota - "Good that you came," And "goodbye," is "Travel well." The language also closely linked the land to the people through geographical names and stories. Lakota philosophical and spiritual concepts often tie together these realms. A word like woímnayankel, expresses notions of awe, humility, and interconnectedness. A Lakota speaker might use this when describing the experience of the northern lights (aurora borealis). The word expresses the humility that a person feels when confronted by the awesomeness of nature while also feeling intimately connected with it.