arena: [17] The original sense of Latin (h)arēna was ‘sand’ (hence the English technical term arenaceous ‘sandy’ [17]). The central, ‘stage’ area of classical amphitheatres, where contests were held, was covered with sand (to soak up the contestants’ blood) and so by metaphorical extension arēna became the term for this central area, and hence for any enclosed place used for contests. The word may ultimately be of Etruscan origin. [arena etymology, arena origin, 英语词源]