stupid is tygelä

tygelä = stupid (adjective) (some things Google found for "tygela": a rare term; a very rare last name; a very rare first name; user names; similarly named Tugela Falls in South Africa is the world's second highest waterfall)

Word derivation for "stupid":
Basque = ergel, Finnish = tyhmä
Miresua = tygelä

To make this word, I tried to use the most common words for stupid in Basque and Finnish. In Finnish the word typerä also means stupid, but also means silly, foolish. In Basque, ergel also means idiotic.

By the way, the word stupid is in paragraph two of Alice's Adventures in Wonderland.