Anacondas are four species of aquatic boa inhabiting the swamps and rivers of the dense forests of tropical South America. The Yellow Anaconda can be found as far south as Argentina. There are two possible origins for the word 'anaconda.' It is perhaps an alteration of the Sinhalese word 'henakanday', meaning 'thunder snake', or alternatively, the Tamil word 'anaikondran', which means 'elephant killer'. It is unclear how the name originated so far from the snake's native habitat; it is likely due to its vague similarity to the large Asian pythons. Local names for the anaconda in South America include the Spanish term matatoro, meaning 'bull killer', and the Native American terms sucuri, yakumama, and jibóia. Anacondas as members of the boa family are sometimes called water boas. The Latin name for Anaconda is Eunectes (from the Greek "ευνήκτης", meaning "good swimmer").