Ottawa or Odawa is a dialect of the Ojibwe language spoken by the Odawa people in southern Ontario in Canada, and northern Michigan in the United States. Descendants of migrant Ottawa speakers live in Kansas and Oklahoma. The first recorded meeting of Ottawa speakers and Europeans occurred in 1615 when a party of Ottawas encountered explorer Samuel de Champlain on the north shore of Georgian Bay. Ottawa is written in an alphabetic system using Latin letters, and is known to its speakers as Nishnaabemwin 'speaking the native language' or Daawaamwin 'speaking Ottawa'.

Ottawa is one of the Ojibwe dialects that has undergone the most language change, although it shares many features with other dialects. The most distinctive change is a pervasive pattern of vowel syncope that deletes short vowels in many words, resulting in significant changes in their pronunciation. This and other innovations in pronunciation, in addition to changes in word structure and vocabulary, differentiate Ottawa from other dialects of Ojibwe.

Like other Ojibwe dialects, Ottawa grammar includes animate and inanimate noun gender, subclasses of verbs that are dependent upon gender, combinations of prefixes and suffixes that are connected with particular verb subclasses, and complex patterns of word formation. Ottawa distinguishes two types of third person in sentences: proximate, indicating a noun phrase that is emphasized in the discourse, and obviative, indicating a less prominent noun phrase. Ottawa has a relatively flexible word order compared with languages such as English.

Ottawa speakers are concerned that their language is endangered as the use of English increases and the number of fluent speakers declines. Language revitalization efforts include second language learning in primary and secondary schools.

Ottawa is known to its speakers as Nishnaabemwin 'speaking the native language' (from Anishinaabe 'native person' + verb suffix -mo 'speak a language' + suffix -win 'nominalizer', with regular deletion of short vowels); the same term is applied to the Eastern Ojibwe dialect. The corresponding term in other dialects is Anishinaabemowin. Daawaamwin (from Odaawaa 'Ottawa' + verb suffix -mo 'speak a language' + suffix -win 'nominalizer', with regular deletion of short vowels) 'speaking Ottawa' is also reported in some sources. The name of the Canadian capital Ottawa is a loanword that comes through French from odaawaa, the self-designation of the Ottawa people. The earliest recorded form is Outaouan, in a French source from 1641.

Ottawa is a dialect of the Ojibwe language, which is a member of the Algonquian language family. The varieties of Ojibwe form a dialect continuum, a series of adjacent dialects spoken primarily in the area surrounding the Great Lakes as well as in the Canadian provinces of Quebec, Manitoba, and Saskatchewan, with smaller outlying groups in North Dakota, Montana, Alberta, and British Columbia. Mutual intelligibility is the linguistic criterion used to distinguish languages from dialects. In straightforward cases, varieties of language that are mutually intelligible are classified as dialects, while varieties of speech that are not mutually intelligible are classified as separate languages. Linguistic and social factors may result in inconsistencies in how the terms language and dialect are used.

Languages spoken in a series of dialects occupying adjacent territory form a dialect continuum or language complex, with some of the dialects being mutually intelligible while others are not. Adjacent dialects typically have relatively high degrees of mutual intelligibility, but the degree of mutual intelligibility between nonadjacent dialects varies considerably. In some cases, speakers of nonadjacent dialects may not understand each other's speech.

A survey conducted during the 1980s and 1990s found that the differences between Ottawa, the Severn Ojibwe dialect spoken in northwestern Ontario and northern Manitoba, and the Algonquin dialect spoken in western Quebec result in low levels of mutual intelligibility. These three dialects "show many distinct features, which suggest periods of relative isolation from other varieties of Ojibwe." Because the dialects of Ojibwe are at least partly mutually intelligible, Ojibwe is conventionally considered to be a single language with a series of adjacent dialects. Taking account of the low mutual intelligibility of the most strongly differentiated dialects, an alternative view is that Ojibwe "could be said to consist of several languages", forming a language complex.