batten [ˈbæt(ə)n] v. i.
1.) To grow better or improve in condition; especially (of animals) to improve in bodily condition by feeding, to feed to advantage, thrive, grow fat.
2.) To feed gluttonously on, glut oneself; to gloat or revel in. (With indirect passive, to be battened on, in modern writers.)
3.) fig. To thrive, grow fat, prosper (especially in a bad sense, at the expense or to the detriment of another); to gratify a morbid mental craving.
4.) To grow fertile (as soil); to grow rank (as a plant) (Oxford English Dictionary 2nd Edition).
Etymology: First found in end of 16th century, but may have been in dialectal use before; apparently adopted from Old Norse batna to improve, get better, recover, from bati, advantage, improvement, amelioration; cognate with Gothic gabatnan, to be advantaged, to be bettered, to profit, a neuter-passive form derived from batan, bôt, batans, to be useful, to profit, to boot. Cf. also Dutch baten, to avail, yield profit; baat, profit, gain, advantage, benefit; and see Grimm s.v. batten. A cognate bat in sense of 'profit, advantage, improvement,' although not known as a separate word in English, is implied in the derivatives batt-able, bat-ful, batt-le (a.).
"The Medical College piles up in its museum its grim monsters of morbid anatomy, and there are melancholy skeptics with a taste for carrion who batten on the hideous facts in historypersecutions, inquisitions, St. Bartholomew massacres, devilish lives, Nero, Caesar Borgia, Marat, Lopez; men in whom every ray of humanity was extinguished, parricides, matricides and whatever moral monsters. These are not cheerful facts, but they do not disturb a healthy mind; they require of us a patience as robust as the energy that attacks us, and an unresting exploration of final causes" (Society and Solitude, Ralph Waldo Emerson, 1870).
(Pochodnie Nerona, Henryk Siemiradzki, 1876)