average (n.)
late 15c., "financial loss incurred through damage to goods in transit," from French avarie "damage to ship," and Italian avaria; a word from 12c. Mediterranean maritime trade (compare Spanish averia; other Germanic forms, Dutch avarij, German haferei, etc., also are from Romanic languages), of uncertain origin. Sometimes traced to Arabic 'arwariya "damaged merchandise." Meaning shifted to "equal sharing of such loss by the interested parties." Transferred sense of "statement of a medial estimate" is first recorded 1735. The mathematical extension is from 1755.
average (adj.)
1770; see average (n.).
average (v.)
1769, from average (n.). Related: Averaged; averaging.