Voracious is an adjective used to describe a wolflike appetite. It might be a craving for food or for something else, such as power, but the word usually denotes an unflattering greediness.
Voracious comes from the Latin vorāre, "to devour." The word is usually associated with swallowing or devouring food in a ravenous manner, but it can be used of someone intensely involved in any activity. Pierre Salinger referred to President Kennedy as a "voracious reader," while Robert Bakker once likened the IRS to a "voracious, small-minded predator."