ラテン語のore rotundoから、丸い口、ore, mouthから、語源的にはoralと同じ、rotundo, roundから、語源的にはround, rotateと同じ。派生語源はvocal。
The odd thing about the word is that its only currency, at least in its non-technical sense, is among those who should most abhor it, the people of sufficient education to realize its bad formation; it is at once a monstrosity in its form & a pedantry in its use. [Fowler]