"Dalit", "Scheduled Caste", "Ex-Untouchable" and "Harijan". These are only some of the many words used to refer to the most oppressed sections of Indian society, "untouchable" in the traditional caste order, performers of the most degrading task, and still today caught in the throes of poverty, discrimination and the remnants of untouchability.
"Dalit" is still probably the most widespread of these terms, but it is not uncontested. Many are uncomfortable with its apparent militancy. It means literally "crushed" or "ground down", and it has an interesting history. It is first found, apparently, in the '30s, when it was used as a Marathi and Hindi translation for the British term "Depressed Classes." (As elsewhere, "classes" here meant "castes", something to remember when we are discussing OBCs.) Ambedkar used it in this way to refer to his Depressed Class conferences, though in English we most often find him using the simple and descriptive term "Untouchable". His conflicts with Gandhi in the early '30s were at least partly a matter of terminology. Gandhi had, for him, the brilliant idea of using the term "Harijan", taken from the bhakti movement. Ambedkar resisted this, just as he resisted Gandhi's attempt to turn an Untouchable League (which Ambedkar thought should take up general issues of civil rights) into a paternalistic organisation controlled by upper-caste Hindus. Ambedkar, and militant Dalits ever since, have seen the word "Harijan" as demeaning and false, hence oppressive.