WordNet sense 1 (an abnormal condition):

abnormalcy, abnormal condition

WordNet sense 2 (retardation sufficient to fall outside the normal range of intelligence):

mental defectiveness

WordNet sense 3 (marked strangeness as a consequence of being abnormal):

freakishness

WordNet sense 4 (behavior that breaches the rule or etiquette or custom or morality):

irregularity