atypical, untypical -- (not representative of a group, class, or type; "a group that is atypical of the target audience"; "a class of atypical mosses"; "atypical behavior is not the accepted type of response that we expect from children")
atypical, irregular -- (deviating from normal expectations; somewhat odd, strange, or abnormal; "these days large families are atypical"; "atypical clinical findings"; "atypical pneumonia"; "highly irregular behavior")
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