The noun inequity describes a situation that’s not fair. If you feel, for example, that your brother gets to do whatever he wants while you must follow the rules to the letter, you might rage against inequity.
The prefix in- in inequity means “not” or “opposite of.” Equity, means "justice or fairness." Put it together and you get inequity: something that’s unfair or unjust. The word can be used to describe a wide range of unfair situations, such as an inequity in a school's buying new equipment for the football team while the field hockey team continues to wear uniforms from 1981.