Final answer:
Gouda is not considered a blue cheese.
Step-by-step explanation:
The cheese that is not considered a blue cheese out of the given options is gouda. While Stilton, Roquefort, and Gorgonzola are all blue cheeses, Gouda is not. Blue cheese gets its name from the blue or green mold, Penicillium roqueforti, that is intentionally added to the cheese during the aging process.