Probably from razah; a species of tree (apparently from its slenderness), perhaps the cypress -- cypress.
see HEBREW razah
תִּרְוָה noun feminine a tree, AV cypress, RV holm-tree, but very dubious: TrNHB 338 PostHast. DB CYPRESS; ᵑ9 ilex, and so M'LeanEncy. Bib. CYPRESS; — absolute ׳ת Isaiah 44:14 (+ אַלּוֺן, "" אֲרָזים).