Isaiah 55:13 uses the word הַסִּרְפַּד which I have seen translated as "brier" or "nettle". What is the precise meaning of this word? Is it used elsewhere?
I think the "meaning" of this word in the context is that Yahweh (God) will lift the curse from the ground. The thorns and thistles (nettles) are the result of the curse on the ground. Isaiah is prophesying that there will be a time when these products of the curse of the ground will be removed, and then substituted with "living" plants that actually bear watery fruit, which will be an eternal testimony that the curse on the ground was finally removed.
As noted, the etymology of the word "הַסִּרְפַּד" subtly hints that it is destined to fire (for burning).
I guess we are into Bible trivia here but it is an unidentified desert plant. It apparently comes from the root word סָרַף which means to burn. Therefore it was probably a prickly bush/plant that 'burned' when one was pricked by it. It is not used anywhere else in the Bible.