olive tree (which is) wild

Concise Bible Dictionary:

Olive Trees
This was the principal source of oil in the East, the trees being extensively cultivated on the sides of the hills, and formed into “olive yards.” See OIL. In the temple, within the holy of holies, Solomon made two cherubim of olive wood; the doors into the oracle were also made of the same wood (1 Kings 6:23-33).
Israel in general is called a green olive tree, fair and of goodly fruit (Jer. 11:16); and a good olive tree, with root and fatness; in contrast to the Gentiles who are compared to a wild olive tree. The fact that the wild olive tree needs grafting gives point to the passage in Romans 11:17-24. God’s two Jewish witnesses in a future day are called the two olive trees and the two candlesticks standing before the God of the earth. They will then be the fruit and light bearers on the earth (Zech. 4:3,11,14; Rev. 11:3-4). The Hebrew is zayith, and the Arabic name is zeitun; it is the Olea Europæa.
Olea Europaea

Strong’s Dictionary of Greek Words:

Greek:
ἀγριέλαιος
Transliteration:
agrielaios
Phonic:
ag-ree-el’-ah-yos
Meaning:
from 66 and 1636; an oleaster
KJV Usage:
olive tree (which is) wild