atypical

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"

deviating from normal expectations; somewhat odd, strange, or abnormal; "these days large families are atypical"; "atypical clinical findings"; "atypical pneumonia"; "highly irregular behavior"