'arborescent' originates from Latin, specifically the word 'arbor', where 'arbor' meant 'tree' and the suffix '-escent' (from Latin '-escens') meant 'becoming'.

'arborescent' changed from Latin/New Latin 'arborescens' (literally 'becoming tree-like') and entered English (via scientific/Latin usage and through French influence) as the modern adjective 'arborescent'; the adverb 'arborescently' is formed by adding the adverbial suffix '-ly'.

Initially it meant 'becoming tree-like' (emphasis on the process), but over time it came to be used primarily in the sense 'resembling a tree' or 'having a branching, tree-like form.'