'arbusculum' originates from Latin, specifically as a diminutive of 'arbor', where 'arbor' meant 'tree' and the diminutive suffix '-culum' implied 'small'.

'arbusculum' appears in Classical and Medieval Latin as a diminutive form of 'arbor' and has been occasionally borrowed into English in learned, botanical, or poetic contexts with little change in form.

Initially it meant 'small tree' in Latin; in English usage as a learned borrowing it retains the basic meaning of 'a small tree or shrub'.