careless is translated as असावधान (asAvadhaan) or लापरवाह (lAparvAh) or बेफ़िक्र (befikra). of these only असावधान is originally a Hindi word, the other two are words from urdu/ arbi etc., i don’t know exactly which. बेफ़िक्र is the closest in meaning to Carefree, the other two mean careless. Another word which is close in meaning to carefree is निश्चिंत (nishchint), but this would also translate to relaxed or having no worries. So, i suppose there is no exact translation of carefree.