It suddenly struck me as odd that the words indolence and indolent have the meanings they do, since they’re transparently from Latin dolere ‘hurt’ (either transitive ‘give pain to’ or intransitive ‘feel pain’) and Latin indolentia does in fact mean ‘freedom from pain.’ I wondered if it was just English that had the sense development to ‘unwilling(ness) to exert oneself,’ but no, the cognate words mean the same thing in all the Romance languages. The OED entry (published 1900) doesn’t help; it just gives the senses “Insensibility or indifference to pain” and “Freedom from pain; a state of rest or ease, in which neither pain nor pleasure is felt” (both obsolete) and “The disposition to avoid trouble; love of ease; laziness, slothfulness, sluggishness” (first in 1710: R. Steele, Tatler No. 132 “Heavy honest Men, with whom I have passed many Hours with much Indolence”), without any explanation of the development. Then I checked with the Trésor de la langue française informatisé and found that the modern sense “Disposition à se donner le moins de peine possible” goes back to at least 1660, and wondered if it was the multivalence of the French word peine, which started out meaning ‘suffering’ and developed a range of senses including ‘trouble, pains’ (of the sort one takes if one is not indolent), that was responsible for the change, and it spread from French to other languages. In any case, I’ll be interested to see the updated entry when the OED gets around to revising it.