disapproval If you say that someone is fattening something such as a business or its profits, you mean that they are increasing the value of the business or its profits, in a way that you disapprove of. They have kept the price of sugar artificially high and so fattened the company's profits. Fatten up means the same as fatten. The Government is making the taxpayer pay to fatten up a public sector business for private sale
If an animal is fattened, or if it fattens, it becomes fatter as a result of eating more. The cattle are being fattened for slaughter The creature continued to grow and fatten