Poison, or just fowsty?

One of my Mom's Newfie speech habits was the cavalier way she used the word poison. "Don't eat that old stuff," she might say, "it'll poison you."

In the early stages of my linguistic development, I lacked the concept of metaphor and equated poison with instant death. If I ate even a crumb of something before my mother advised against it as "poison," I was terrified I might drop dead at any moment. After surviving a number of expected "poisonings," it occurred to me to wonder if I might have misunderstood the word. One day I decided to ask for clarification.

"Mompy, would eating this moldy bread kill me?"

To my astonishment, my mother scoffed at the idea. "No, indeed, my dear," she said. "But it's no good." She wrinkled her nose and pointed to the blue patch. "See? It's fowsty."

Now I haven't heard that word since Mom passed away, and it may not be in the dictionary, but according to a facebook discussion, it's still around. The alternative spelling is fousty.