Synonyms for Atypical (same or very similar meaning)
WordNet sense 1 (not representative of a group, class, or type):
untypicalWordNet sense 2 (deviating from normal expectations; somewhat odd, strange, or abnormal):
irregularWordNet sense 3 (not normal; not typical or usual or regular or conforming to a norm):
abnormalFrom the ODE community, based on WordNetadd/edit