Easton's Bible Dictionary
More properly sycomore (Hebrews shikmoth and shikmim, Gr. sycomoros), a tree which in its general character resembles the fig-tree, while its leaves resemble those of the mulberry; hence it is called the fig-mulberry (Ficus sycomorus). At Jericho, Zacchaeus climbed a sycomore-tree to see Jesus as he passed by (Luke 19:4). This tree was easily destroyed by frost (Psalm 78:47), and therefore it is found mostly in the "vale" (1 Kings 10:27; 2 Chronicles 1:15: in both passages the R.V. has properly "lowland"), i.e., the "low country," the shephelah, where the climate is mild. Amos (7:14) refers to its fruit, which is of an inferior character; so also probably Jeremiah (24:2). It is to be distinguished from our sycamore (the Acer pseudo-platanus), which is a species of maple often called a plane-tree.
Noah Webster's New International Dictionary of the English Language
1. (n.) A large tree (Ficus Sycomorus) allied to the common fig. It is found in Egypt and Syria, and is the sycamore, or sycamine, of Scripture.
2. (n.) The American plane tree, or buttonwood.
3. (n.) A large European species of maple (Acer Pseudo-Platanus).