Merriam-Webster Collegiate Dictionary - aberrant

 I. adjective  Etymology: Latin ~-, aberrans, present participle of aberrare to go astray, from ab- + errare to wander, err  Date: circa 1780  1. straying from the right or normal way  2. deviating from the usual or natural type ; atypical  • aberrance noun  • aberrancy noun  • ~ly adverb  II. noun  Date: 1938  1. an ~ group, individual, or structure  2. a person whose behavior departs substantially from the standard