Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
SHIT'TIM-WOOD (from the shittah tree, Isa 41:19) was much used in constructing and furnishing the tabernacle. Ex 25:15-16. The only timber tree of any size now found in the Arabian desert is the seyal (Acacia seyal). " There can be little doubt that this acacia was once abundant in the Sinai region and is the shittim of Scripture. Shittim-wood (Acacia). The seyal is a very thorny tree, somewhat resembling our apple tree when seen from a distance, but with decompound leaves, small leaflets, and little yellow balls of fibrous bloom, followed by locust-like pods.
Its wood is close-grained, hard, brownish-hued, and well adapted for cabinet-work. From cuts or cracks in the trunk and limbs of this and one or two other acacias gum-arabio exudes, and is collected. The burning bush, Ex 3:2, on philological grounds, is believed to be a similar but smaller tree, the sunt (Acacia Nilotien), found occasionally in this region. Several localities mentioned in the Bible were named from the shittim.