black plum
noun
1Any of several plum trees with dark-coloured fruit; the fruit of any of these trees; (now rare ).
2Any of several other trees with dark-coloured plum-like fruit; especially a small tree of eastern Australia, Diospyros australis (family Ebenaceae).
Origin
Early 17th century; earliest use found in John Parkinson (1566/7–1650), apothecary and herbalist.