Relating to or characteristic of barbarians; crude, uncivilized, or lacking in culture and refinement.
From 'barbarian' plus the adjectival suffix '-ical' (an alternative to '-ic'). This form is archaic but was used in Early Modern English to describe supposedly uncivilized peoples and behaviors.
The '-ical' ending made words sound more scholarly and formal, which is why 'barbarical' appears in Shakespeare and earlier texts even though 'barbaric' was more common—it's language trying to sound important!
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