blue fig
noun
1Any of numerous cultivated varieties of the fig tree (Ficus carica) having blue or purple fruits (more fully blue fig tree).
2 Australian the large tree Elaeocarpus grandis (also called E. angustifolius) (family Elaeocarpaceae) of eastern Australia, which has small blue fruits.
Origin
Early 17th century; earliest use found in Ben Jonson (?1573–1637), poet and playwright.