Relating to or constituting the essential or distinctive character of someone or something; typical or distinctive.
From 'characteristic' with the older suffix '-al' attached (making '-ical'), an archaic or dialect variant of 'characteristic' used in older English texts.
This word is almost never used anymore—it's been replaced by 'characteristic'—but you might find it in Shakespeare or old medical texts, showing how English simplified its vocabulary over time.
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