"If you're one of two million people on Earth who are conversant in Esperanto, you'll know exactly what "Sentima" means."
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I had to think for a while before I realized that sentima is without fear. I guess I am not among the conversant.

At first, I thought it had to do with being sentient.

Alkanadi:"If you're one of two million people on Earth who are conversant in Esperanto, you'll know exactly what "Sentima" means."
[url=/whatson-story/6701801-leonard-turnevicius-hcc-choristers-pick-music-with-a-message/]Link[/url]

I had to think for a while before I realized that sentima is without fear. I guess I am not among the conversant.

At first, I thought it had to do with being sentient.

You need more practice. Sen + adjective is very common compound in esperanto:
senaga, senakcenta, senaktiva, senakva, senĉesa, senorda, senforta, senkapa, senkuraĝa, sendorma...