Relative deprivation refers to the perception that you (or your group) have less than you deserve, less than you have been led to expect, or less than people similar to you have
Other /More definition:
Relative deprivation refers to the perception that one is less well off than others to whom one compares oneself; the perception that one is relatively deprived in comparison with other people.
Moreover, Relative deprivation refers to man's a perceived disadvantage in social or economic standing based on his comparison to others members of his society.