What is the origin of "nonchalance?"
Solution 1:
It comes from the French nonchalant, which means indifferent.
From etymonline.com:
1670s, from Fr. nonchalant, prp. of nonchaloir "be indifferent to, have no concern for" (13c.), from non- "not" + chaloir "have concern for," ultimately from L. calere "be hot" (see calorie). French chaland "customer, client" is of the same origin.