The word "oleander" appears as far back as the first century AD, when the Greek physician Pedanius Dioscorides cited it as one of the terms used by the Romans for the plant. Merriam-Webster believes the word is a Medieval Latin corruption of Late Latin names for the plant: "arodandrum" or "lorandrum", or more plausibly "rhododendron" (another Ancient Greek name for the plant), with the addition of "olea" because of the superficial resemblance to the olive tree ("Olea europea") Another theory posited is that "oleander" is the Latinized form of a Greek compound noun: "οllyo" (ὀλλύω) 'I kill', and the Greek noun for man, "aner", genitive "andros" (ἀνήρ, ἀνδρός). ascribed to oleander's toxicity to humans.