extreme: [15] Etymologically, extreme is the latinate equivalent of the native English utmost. It comes via Old French extreme from Latin extrēmus ‘farthest, last, excessive’, which began life as a superlative form based on Latin ex ‘out’ – hence originally ‘most out, utmost’. The underlying notion of ‘furthest outlying’ still survives in, for example, the use of extremities for the ‘hands’ or ‘feet’. [extreme etymology, extreme origin, 英语词源]