Boyd’s Bible Dictionary:
The evergreen, whose wood is so prized by engravers (Isa. 41:19; 60:13).
Concise Bible Dictionary:
What tree is referred to under the name teashshur is not known: the ancient versions translate it “cedar, fir, poplar.” It is probably a species of cedar, called sherbin in the East (Isa. 41:19; Isa. 60:13).