Definition
A 'heteroploid' organism has an abnormal number of chromosomes, differing from the usual set for its species. Think of it like having too many or too few LEGO bricks in a set. It can result from errors during cell division. While often associated with genetic disorders, it plays a vital role in evolution. The term 'aneuploid' is often used interchangeably. It's the opposite of having the correct number of chromosomes.