Feral (from Latin fer meaning wild beast), in its modern definition, describes an animal who is wild or untamed and rarely is applied to an uncultivated plant. Also of, pertaining to, or resembling a wild beast. Feral’s secondary application is to an animal or cultivated plant species that have lapsed into a wild state from their previous domesticated condition. Organisms that may be portrayed as feral can often be associated with vocabularies that imply a sense of brutality or savageness. Feral bodies, such as plants and animals, pose both a positive and negative effect on rural ecosystems. The addition of a feral body into a non-indigenous habitat may greatly affect the precision at which an ecosystem works. Feral organisms possess the power to contribute to an ecosystem by eliminating species setbacks, i.e. an overpopulation of aggressive insects. On the other hand, a feral organism may contribute to a withdrawal of vital resources, i.e. fresh food and water, from native species. Zoologists generally exclude from the ‘feral’ category, an animal who was previously wild before their domestication and release back into nature. For example, a tiger who escapes from a zoo may not be classified as a feral creature.
A feral person may not necessarily be uncivilized, but perhaps driven mad to the point of animal instincts. A person who acts in a feral manner is brutal and savage. In war, soldiers may turn feral and act more a wild animal than human, more often happening in times where hand-to-hand combat was common.
Feral was also used to portray one who was of a deadly nature. In Latin, fērāl is of or pertaining to funeral rites or to the dead. This usage, though more uncommon and not the usage of today, was used to describe diseases that were otherwise incurable and ultimately caused death.
"feral 1." Oxford English Dictionary. http://www.oed.com/view/Entry/69301 (accessed November 21, 2012).
"feral 2." Oxford English Dictionary. http://www.oed.com/view/Entry/69302 (accessed November 21, 2012).