He explained that that was Welsh for 'afternoon'.
I asked him where he learned it. Duolingo, apparently. I said it didn't sound like he was pronouncing it correctly (not that I know much about Welsh, mind you), and doesn't Duolingo have an audio component?
Well yes, he said, it does. But he couldn't hear it because he had the sound turned off.
"Because I was doing it in French class."
He said "I thought maybe you wouldn't be mad at me."
Mad? No. Delighted. My dear one struggled terribly with French during this last year at school. For all his teacher's valiant efforts and kind encouragement, the focus of the course she was teaching had switched to rote memorization of verb conjugation, and he just couldn't stand to learn that way.
Finally, we're back to unschooling, and he can learn whatever languages he wants, however he wants.
Thank you Prince Ea!