indolent: [18] Historically, indolent means ‘feeling no pain’ – indeed, that is how it was used as a technical medical term in English in the 17th and 18th centuries. It comes from late Latin indolens, which was based on the Latin verb dolere ‘suffer pain’ (source also of English dolour [13] and doleful [13]). English took the term directly from Latin, but meanwhile in French indolent had broadened out in meaning via ‘insensitive’ to ‘inactive, lethargic, lazy’, and that is the basis of the current English use of the adjective, acquired in the early 18th century. => doleful, dolour
