Definition of battens:
(v) :
(intransitive) (often passive voice) Followed by on: to eat greedily; to glut.
(v) :
(intransitive) (figurative) Followed by on: to prosper or thrive, especially at the expense of others.
(v) :
(intransitive) To become better; to improve in condition; especially of animals, by feeding; to fatten up.
(v) :
(intransitive) Of land, soil, etc.: to become fertile; also, of plants: to grow lush.
(v) :
(intransitive) (figurative) To gloat at; to revel in.
(v) :
(intransitive) (figurative) To gratify a morbid appetite or craving.