There's a technical definition in mechanism design: a mechanism (say for allocating goods) is Fair if all participants derive equal utility from participating.

Could you provide a reference for this? The use of interpersonal comparison of utility here surprises me.

I thought that the usual definition of fairness took into account both what you gain from your participation and what other people gain from your participation.

ETA: Are you referring to the same notion of fairness as in this famous paper by Rabin?