Taking advantage of a person.
Simply put, exploitation should be impossible between equals. To exploit persons is to use an advantage over them -- to their disadvantage.
An uncoerced transaction can still be exploitation if the terms of contract are dictated to someone's disadvantage. The exploitation lies in the "conditions of compulsory restriction and limitation under which such contract" is made.
[quoting from Benjamin Tucker's essay, The Aboliton of Interest]
Individualist Anarchism sees the exploitation of certain groups or classes as the visible symptom of a deeper problem whose root cause is coercive monopoly.
The individualist does not sanction the use of force to fight the symptom, but only to fight the coercive root cause itself.
bkMarcus, The Aboliton of Exploitation
[bk]
... the allegation that an exchange has unduly favoured one of the parties ...
Anthony de Jasay, "Your Dog Owns Your House"
[deJasay]
'Exploitation' is a word often used but rarely defined. In its most literal meaning -- I "exploit" you if I in some way benefit from your existence -- it is the reason human society exists. We all benefit from one another's existence. We all exploit each other. That is why we associate with each other. But as the word is usually used, it carries the implication of one person benefiting from harming another, or at least of one person's benefitting unfairly, at the expense of another. This usage we derive from Marx's theory of the exploitation of labor.
David Friedman, The Machinery of Freedom
[friedman]
The illusion persists that those with much are villains. With it as a necessary corollary goes the illusion that those who have little or nothing are the heroes who are deserving of every good thing in life.
This is the Marxist argument. It assumes that those who are capable of producing abundance, in some way exploit those who are incapable of producing much of anything. How does one "exploit" the impoverished? The concept is nonsense. One does not take from those who have nothing worth taking.
Robert LeFevre, Capitalism
[leFevre]