The word Métis (the singular, plural and adjectival forms are the same) is French, and related to the Spanish word mestizo. It carries the same connotation of "mixed blood"; traced back far enough it stems from the Latin word mixtus, the past participle of the verb "to mix".
A well-known Métis event was the battle of Seven Oaks.
The most famous Métis was Louis Riel who led them in the failed North-West Rebellion in the area now known as Manitoba. After the rebellion the Canadian government effectively deprived the Métis of land. The province of Alberta distributed land to Métis in 1938 to correct what it believed to be an inequity, but Saskatchewan and Manitoba have not followed Alberta's lead.
The Métis are not recognized as a First Nation by the Canadian government and do not receive the benefits granted to other aboriginal groups. The new Canadian constitution of 1982, however, recognizes Métis as an aboriginal group and has enabled individual Métis to sue successfully for recognition of their traditional rights, such as rights to hunt and trap.
Métis National Council (http://www.metisnation.ca/)