Insouciance

Used in a sentence:

• The robot traveled across the lava pits with insouciance that bordered on self-destructive but held the medicine as a parent might their child.

Source: Wiktionary

Commentary:

Before you ask, no. I don’t know how to pronounce it. It’s a word stolen from French I believe. So I am sure most of the letters don’t sound like how they are supposed to sound. Interestingly enough, a noun for a meaning usually reserved for an adjective, ie carelessness or indifference. I believe it’s more common form is apathy but I might start using this word more.  If your curious how to be sure you’ve used this word correctly, just replace it with the word ‘care’ and making sure the word ‘caring’ doesn’t make sense, and you’ve got it!