'arbor' originates from Latin, specifically the word 'arbor', where the root meant 'tree'.

'arbor' entered Middle English (also influenced by Old French 'arbre' and Anglo-French forms) and developed into the English word 'arbor' (with the alternative spelling 'arbour' in British English).

Initially it meant 'tree' in Latin; over time in English it came to refer both to tree-related structures (a shady bower or framework for climbing plants) and, by extension, to a central shaft or spindle (a tree-like axis) in machinery.