A common marine insurance term. An early meaning (c.1500) of the word average is 'damage sustained at sea'. The root is found in Arabic as awar, in Italian as avaria and in French as avarie. Hence an average adjuster is a person who assesses an insurable loss. Marine damage is either particular average, which is borne only by the owner of the damaged property, or general average, where the owner can claim a proportional contribution from all the parties to the marine venture. The type of calculations used in adjusting general average gave rise to the use of 'average' to mean 'arithmetic mean'.