hectare n.

1590s, from Latinized form of Greek hekatombe, properly (and literally) "offering of 100 oxen," but generally "a great public sacrifice." It is a compound of hekaton "one hundred," which perhaps is dissimilation of *hem-katon, with hen, neuter of heis "one" + *katon "hundred." The second element is bous "ox" (from PIE root *gwou- "ox, bull, cow"). The first month of the Attic calendar (corresponding to July-August) was Hekatombaion, in which sacrifices were made.

1530s, "vacant piece of ground," from Latin area "level ground, open space," used of building sites, playgrounds, threshing floors, etc.; which is of uncertain origin. Perhaps an irregular derivation from arere "to become dry" (see arid), on notion of "bare space cleared by burning." The generic sense of "any particular amount of surface (whether open or not) contained within any set of limits" is from 1560s. Area code in the North American telephone systems is attested from 1959.