Noun
Any of several species resembling a typical olive tree from plant families some of which are only very distantly related.
Bontia daphnoides (family Scrophulariaceae; bastard olive)
Several species in the genus Elaeagnus (family Elaeagnaceae), particularly:
Elaeagnus angustifolia (silver berry, oleaster, Persian olive)
Elaeagnus latifolia (oleaster)
Halesia carolina (family Styracaceae; Carolina silverbell, little silverbell)
Nyssa aquatica, an American swamp-growing tree (family Cornaceae; water tupelo)
Subspecies of Olea europea, which includes the cultivated olive (family Oleaceae)
Olea europaea subsp. cuspidata
Olea europaea subsp. europaea (syn. Olea oleaster)
Cartrema americana (syn. Osmanthus americanus; devilwood, American olive; family Elaeagnaceae)
Source: en.wiktionary.org