To make mad or angry; to drive to madness or frustration; an archaic or dialectal variant of 'bemad' or related to 'madden'.
From 'be-' (intensifying prefix) plus 'madden' (to make mad), or possibly from 'bemad' with an additional suffix. Part of the Middle English and Early Modern English verb-building system.
Rather than using 'bemad,' speakers could also say 'bemadden'—English had multiple ways to express the same concept, which is why so many of these 'be-' verbs competed and most eventually disappeared.
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