Fatten

verb

1. To cause (a person or animal) to be fat or fatter.

   "We must fatten the turkey in time for Thanksgiving."

2. (of a person or animal) To become fat or fatter.

   "He gradually fattened in the five years after getting married."

3. To make thick or thicker (something containing paper, often money).
4. To become thick or thicker.
5. To make (soil) fertile and fruitful.

   "to fatten land"