Of, relating to, or characteristic of butchery; brutal, savage, or marked by bloodshed.
From 'butcher' plus the adjective suffix '-ous' (from Latin '-osus'). The '-ous' suffix is extremely common in English and often suggests a quality or abundance of something (dangerous, glorious, famous).
Words ending in '-ous' tend to sound more formal and Latinate than their '-y' counterparts—compare 'butcherous' (rare, formal) to 'butcherly' (also archaic). These competing suffixes show English's multiple vocabulary layers.
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