mid-15c., exorbitaunce, "a deviation from what is right, a transgression of normal limitations" (a sense now archaic or obsolete), from exorbitant + -ance. Sense of "extravagance in degree or amount, excessiveness" is from 1640s. Related: Exorbitancy.
exogamy
exogenous
exonerate
exoneration
exorable
exorbitance
exorbitant
exorcise
exorcism
exorcist
exoskeleton