noun
BAD : The cooker puts too much salt in the food.
GOOD : The cook/chef puts too much salt in the food.
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cooker (AmE stove ) = a piece of equipment that you use for cooking food: 'I've never used a gas cooker before.'
cook = a person who cooks: 'My sister is a superb cook.'
chef = a cook who works in a restaurant: 'Jean-Paul is training to be a chef.'