It is an adjective.
Meaning : away from the normal .It means deviating from main course.If suppose say there's a debate going on and it is heated up in such a way and every one is talking everything else which is not the topic then we use aberrant.
So aberrant is used to specify abnormal things or when departing from right course .
Root of the word : ab = away, apart, off err = wander
Synonyms : deviant, abnormal, anomalous,wandering
Antonyms : typical, regular, characteristic
aberrance, aberrancy - noun
aberrantly - adverb
1)He is depressed and that is the root cause of his aberrant behaviour.
2)This aberrant situation could not have been handled better.
3)He is most aberrant person I have ever seen.
4)The argument had become aberrant and no one is able to make head and tail of that.