Wiki article on this topic:
The olive, known by the botanical name Olea europaea, meaning "European olive", is a species of small tree in the family Oleaceae, found in the Mediterranean Basin from Portugal to the Levant, the Arabian Peninsula, and southern Asia as far east as China, as well as the Canary Islands and Réunion. The species is cultivated in many places and considered naturalized in all the countries of the Mediterranean coast, as well as in Argentina, Saudi Arabia, Java, Norfolk Island, California, and Bermuda. Olea europaea is the type species for the genus Olea.
The olive's fruit, also called the olive, is of major agricultural importance in the Mediterranean region as the source of olive oil; it is one of the core ingredients in Mediterranean cuisine. The tree and its fruit give their name to the plant family, which also includes species such as lilacs, jasmine, Forsythia, and the true ash trees.
The word "olive" derives from Latin ŏlīva , possibly through Etruscan 𐌄𐌋𐌄𐌉𐌅𐌀 from the archaic Proto-Greek form *ἐλαίϝα.
The word "oil" originally meant "olive oil", from ŏlĕum, ἔλαιον. Also in multiple other languages the word for "oil" ultimately derives from the name of this tree and its fruit.
The oldest attested forms of the Greek words are the Mycenaean 𐀁𐀨𐀷 , e-ra-wa, and 𐀁𐀨𐀺 , e-ra-wo or 𐀁𐁉𐀺 , e-rai-wo, written in the Linear B syllabic script.
The olive tree, Olea europaea, is an evergreen tree or shrub native to the Mediterranean, Asia, and Africa. It is short and squat, and rarely exceeds 8–15 m in height. 'Pisciottana', a unique variety comprising 40,000 trees found only in the area around Pisciotta in the Campania region of southern Italy often exceeds this, with correspondingly large trunk diameters. The silvery green leaves are oblong, measuring 4–10 cm long and 1–3 cm wide. The trunk is typically gnarled and twisted.
The small, white, feathery flowers, with ten-cleft calyx and corolla, two stamens, and bifid stigma, are borne generally on the previous year's wood, in racemes springing from the axils of the leaves.