Only Brazil do not have Spanish as an official language. The official language in Brazil is Portuguese.
Here is a list of South American countries that do not have Spanish as an official language. Some of these countries speak spanish as a common language though, even though it's not official:ArgentinaBrazilChileFalkland IslandsFrench GuianaGuyanaNicaraguaSurinameUruguay
Spanish is spoken in more Latin American countries than any other language.
Brazil, Guyana, Surinam are three countries where Spanish is not the official language. French Guyana is a territory in South America where Spanish is not the common language.
Spanish is the official language of most Latin American countries.
8
Swahili
There is no language that is spoken in all South American countries except one. You're thinking of Spanish, but Spanish is not spoken in:BrazilGuyanaFrench GuianaSurinameThe Falkland Islands
Castellano is the another way to say the spanish language in spanish.
Spanish is spoken in many South American countries, but it is only "official" in these 7 countries: Colombia Peru Venezuela Ecuador Bolivia El Salvador Paraguay
Spanish is spoken in all 7 Central American Countries however English remains the only Official language of Belize. (most Belizeans are bilingual)
Spanish is the primary language. In some parts of South America there is still a population that speaks Mayan and other Native American languages.
Spanish - because most of the South American countries speak that language, and Brazil because it is spoken in the largest country on the continent.