My friend tells me the word, "nalanthalas" is a literary term. I've
looked everywhere, but can find no evidence that he is telling the
truth. My friend says, "It's a literary term, but nobody I know can
tell me what it means." I told him it sounds like any oxymoron, but he
insists it's a real word. So, my question: What does "nalanthalas"
mean?

I suspect that your friend is pulling your leg.

This word does not appear in the unabridged Oxford English Dictionary,
nor in the unabridged Merriam-Webster Third New International
Dictionary.

If your friend doesn't know what the word means, can he recall where
he encountered the word?

How is it pronounced?  Where are the accents, primary and secondary?

I'm going to check with my friend this weekend on the pronunciation of
"nalanthalas". I will also find out where he heard in and in what
context.
Thanks for keeping up with this question. I'll post again when I know some more.

Pink, you could be right that it's a gag, but it's also possible that
if we know how it sounds, we could recognize a real literary term that
might have been misheard.  I remember when I was a kid a pen-pal
overseas asked me what kind of music I liked, and I mentioned
Tchaikowsky.  She wrote back eagerly to tell me that she loved
Tchaikowsky's "One Leg."  I puzzled over that for some time until I
said it aloud, just like that, with the composer's name in front of
it, and suddenly heard the name of a familiar ballet, as it might have
sounded announced over the radio.

Apteryx