Parseltongue

Parseltongue is the language of snakes and of magical serpents such as the Basilisk, and to anyone who does not speak it, it sounds like hissing. A witch or wizard able to speak it is called a Parselmouth. The ability is rare and almost always inherited, and in Britain it carries an association with the Dark Arts that draws fear and mistrust towards anyone known to have it. Beyond talking with serpents, a Parselmouth can influence their will to some degree, and two Parselmouths can speak the language to each other.