From the same as tsemer; fleeciness, i.e. Foliage -- highest branch, top.
see HEBREW tsemer
H6788. tsammereth
צַמֶּ֫רֶת noun feminine tree-top (possibly from woolly, feathery,appearance); — ׳צ construct, of cedar (in figurative) Ezekiel 17:3, 22, so suffix צַמַּרְתּוֺ 31:3, 10; of tall trees in General, צַמַּרְתָּם 31:14.