prey (up)on someone or something
Fig. to take advantage of someone or something. (See also prey on something. Upon is formal and less commonly used than on.) The people of that island prey on tourists and do not give them good treatment. I really don't want to seem to prey upon your kindness.
prey on something
[for an animal] to feed on another animal as a matter of habit or preference. Owls prey on mice. Many birds prey on snakes.
1. Plunder or pillage; also, make a profit at someone else's expense, victimize. For example, Vikings preyed on the coastal towns of England, or The rich have been preying on the poor for centuries. [Late 1500s]
2. Hunt, especially in order to eat, as in Their cat preys on all the rodents in the neighborhood. [c. 1600]
3. Exert a baneful or injurious effect, as in Guilt preyed on his mind. [c. 1700]
1. To hunt and kill something for food: Owls prey on mice.
2. To exploit or make a profit at the expense of someone; take advantage of someone: Pickpockets often prey on unsuspecting tourists.
3. To exert a harmful or injurious effect on something or someone: Guilt preyed on him, and eventually led him to confess.