Not regular; lacking in regularity, consistency, or proper order; irregular.
From dis- (negation) + regular (from Latin 'regularis', conforming to a rule, from 'regula' meaning rule). Though 'irregular' is the standard form, 'disregular' was used in Early Modern English.
'Disregular' is a beautiful example of a 'lost adjective'—it existed alongside 'irregular' but one form eventually dominated through random historical chance, not because one was better, just because people gradually chose one over the other.
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