It's possible:
* It's a misspelling: Perhaps you meant to write a different word or phrase. Can you double-check the spelling or provide more context?
* It's a made-up word: It could be a fictional term from a book, game, or other creative work.
* It's a code or cipher: It could be a message encoded in a specific way.
Please provide more information so I can help you figure out what "amataca tesder" actually means!