a large fruit tree of the mulberry and fig family: probably the black mulberry, possibly the sycamore fig.
This word names a specific large tree, and it appears only once in the New Testament, in the saying where Jesus tells his followers that faith the size of a mustard seed could uproot this tree and plant it in the sea. The trouble is that scholars are genuinely split over which tree Jesus meant.
In the older, literary Greek of writers like Theophrastus, the word meant the black mulberry, a hard-wooded tree that is famously difficult to pull up. But in the everyday Greek of Egypt and in the Greek Old Testament, the same word meant the sycamore fig, a completely different tree of the same broad family whose figs grow straight out of the trunk. So a first-century reader could have heard it either way.
Two strong clues pull in opposite directions. Luke himself uses a second, clearly different word (συκομορέα) for the sycamore fig that Zacchaeus climbs a couple of chapters later, and the fact that he bothers to use two different words is the best single reason to think this one is the mulberry. On the other side, Luke's Greek is steeped in the Old Testament, where this exact word is always the sycamore fig, which would pull the two words back together.
Happily, the point of Jesus' saying does not depend on the answer. Both trees are large, long-lived, and deeply rooted, so either one flung into salt water, where no tree can grow, makes the same picture: mustard-seed faith doing what looks flatly impossible.
Disputed
Which tree συκάμινος denotes in Luke 17:6: the black mulberry (Morus nigra) or the sycamore fig (Ficus sycomorus).
- contestedThe black mulberry. Luke deliberately distinguishes this word from συκομορέα, which he uses for the sycamore fig at 19:4, so the classical botanical distinction should stand.; BDAG (F. W. Danker, 3rd ed., 2000), s.v. συκάμινος; J. P. Louw and E. A. Nida, Greek-English Lexicon of the New Testament Based on Semantic Domains (UBS, 1988-89), sections 3.5-3.6; A. T. Robertson, Word Pictures in the New Testament, on Luke 17:6; M. Zohary, Plants of the Bible (Cambridge University Press, 1982)
- contestedThe sycamore fig, the same tree as συκομορέα in 19:4. Luke's Greek is shaped by the Septuagint, where this word consistently renders the Hebrew word for the sycamore fig.; LSJ (Liddell-Scott-Jones, 9th ed. with Supplement), s.v. συκάμινος, sense II; J. A. Fitzmyer, The Gospel According to Luke X-XXIV, Anchor Bible 28A (1985), pp. 1142-43; I. H. Marshall, The Gospel of Luke, NIGTC (1978), pp. 643-45
- minorityThe distinction is moot: in first-century Palestinian Greek the two words were largely interchangeable, as already noted by Dioscorides and reflected in the Peshitta and Vulgate.; F. Bovon, Luke 2, Hermeneia (2013), on Luke 17:6; J. B. Green, The Gospel of Luke, NICNT (1997), pp. 611-14