What term describes the condition of having an incorrect number of chromosomes?

The term that describes the condition of having an incorrect number of chromosomes is aneuploidy. This condition arises when there is a gain or loss of one or more chromosomes, resulting in an abnormal number compared to the standard diploid number for that organism. Aneuploidy can lead to various genetic disorders, such as Down syndrome, which is caused by an extra copy of chromosome 21.

Polyploidy refers to having one or more extra sets of chromosomes, which is a common occurrence in plants but is not the same as having an incorrect number of individual chromosomes. Homologous chromosomes represent pairs of chromosomes that have the same genes but potentially different alleles; this term does not relate directly to chromosome number. Diploid signifies a normal chromosome number for somatic cells in many organisms, where pairs of homologous chromosomes are present, meaning the term does not reflect abnormal chromosomal conditions.