Probably from Vulgar Latin *aerūgina, from Latin aerūgō, aerūginem (“copper rust”), with a later change of accent/emphasis to the penultimate syllable in Romanian, which may have occurred due to the influence of derivatives such as rugini, ruginos, etc. Compare Italian ruggine, Friulian ruzin; cf. also Asturian roña. Alternatively, and less likely, from Latin rūbīginem, accusative of rūbīgō (“rust”), also with a change of emphasis; compare Spanish robín. Cognate to Aromanian arudzinã.
rugină f (plural rugini)