also Algonkian, Native American people and language family, 1885, an ethnologist's word, from Algonquin, name of one of the tribes, + -ian. Both forms of the name have been used as adjectives and nouns. They originally were spread over a wide area of northeast and north-central North America, from Nova Scotia (Micmac) to Montana (Cheyenne). From 1890 in geology.

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Definitions of Algonquian from WordNet
Algonquian (n.)
a member of any of the North American Indian groups speaking an Algonquian language and originally living in the subarctic regions of eastern Canada; many Algonquian tribes migrated south into the woodlands from the Mississippi River to the Atlantic coast;
Synonyms: Algonquin
Algonquian (n.)
family of North American Indian languages spoken from Labrador to South Carolina and west to the Great Plains;
Synonyms: Algonquin / Algonquian language
Algonquian (adj.)
of or relating to an Algonquian tribe or its people or language;
Synonyms: Algonkian / Algonquin