Atypic

Not typical; not conforming to a type or normal standard; unusual or atypical.

From prefix 'a-' (not) + 'typic' (from Greek 'typikos,' meaning 'of or belonging to a type'). The Greek root 'typos' originally meant 'blow' or 'mark,' then evolved to mean 'impression' or 'model.' The 'a-' prefix negates the quality of being typical.