oleander

Oleander comes from French oléandre, from Medieval Latin oleandru, from Late Latin lorandrum — a word that may itself be an alteration of rhododendron.

The facts here trace a shift in form rather than meaning: the Late Latin lorandrum is thought to have twisted its shape, perhaps under the influence of rhododendron, before settling into oleandru and then oléandre.

If the theory about lorandrum's alteration holds, oleander shares a distant thread with rhododendron, another word for a flowering shrub.