What you might call a raita in the North of India is called a pachadi in the states of Tamil Nadu and Kerala in the South of India, and is called a Tambli in some other parts of India. It is a dish typically made of finely chopped or blended cooked vegetables with yoghurt, coconut, green or red chilies and tempered in oil with mustard seeds, ginger and curry leaves.
Pachadi means pounded. In Kerala and Tamil Nadu pachadi is eaten fresh and commonly eaten with rice and a lentil curry. There are many varieties made of the same key recipe.
There is no real approximation to a pachadi outside of India. The closest in western cuisine is a side dish or dip, or a yoghurt salad. It is sometimes incorrectly referred to as a condiment, but unlike traditional western condiments like salt, pepper, mustard and horseradish that made dishes more spicy, these dishes have a cooling effect from the yoghurt, to contrast with spicy curries.
It is also sometimes called a pickle – this is incorrect, at least in the states of Tamil Nadu and Kerala.
Pachadis from the state of Andhra are vegetables ground to a paste with spices but without yoghurt, and these are commonly called chutneys. They are more equivalent to the Tamil Nadu dish called Thogayal, a pureed vegetable with spices, also referred to as a chutney.