meaning of 'rotten'

[Klpno]

Hello everyone.

I'd like to ask about the meaning of 'rotten' in the following context.

They had found a pattern. He would ask some little questions, and she would answer his former question.
"The word 'mountain,' he said. "Do you know what it means?"
She smiled now, glancing at his face. "Do you?"
He allowed himself the pleasure of a wise nod. "It is an ancient word," he answered. "The oldest texts employ it. But even by then, the word had fallen into a rotten disuse.

Does 'rotten' mean 'complete' in this case?

[Jamie (K)]

In this case "rotten" means that the word has been very seldom used for a very long time, and that it is probably sad that it isn't used anymore.

[Klpno]