Ante here comes from the Latin word for 'before', and as an English term it was originally (in the early 19th century) a term in poker and similar gambling games, meaning 'a stake put up by a player before drawing cards'.
Unlike the blinds, everyone at the table pays the ante when they are in play. Antes tend to be much smaller than the blinds and are usually between 10-15% of the big blind. For example, a tournament with antes in play may have a 500 small blind and a 1,000 big blind. Antes will likely be between 100 and 150.