term:

Lesion

lesion n

[Anglo-French, damage, injury, from Latin laesio, from laedere to injure]
in the civil law of Louisiana
: loss from failure to receive a threshold amount or value (as one-half market value) for immovable property conveyed or transferred by a commutative contract (as a sale or exchange) [a new partition may be demanded for the least "Louisiana Civil Code"] called also lesion beyond moiety compare unjust enrichment

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.