A marriage between unequals in rank was disparaging; such a marriage involved dishonour and/or disgrace. *Bracton says of an heir in wardship: 'A lord may give the heir in marriage when and where he wishes, provided [the heir] is not disparaged.' Later, *Magna Carta states explicitly: 'Heirs shall be married without disparagement'. [< OldFr. desparage < dis- = a negative lack + parage = equality]
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.