The chromosomes are named. Each chromosome of a pair, in 22 of the 23 pairs, is similar to the other of that pair. The chromosomes of these 22 pairs are named as they are numbered. There are two chromosome 1's, two chromosome 2's, two chromosome 3's etc...up to having two chromosome 22's. Chromosomes 1 through 22 are also called, "autosomes". The 23'rd pair consists of two "x" chromosomes in a woman and one "x" chromosome and one "y" chromosome in a male. The x and y chromosomes are also called, "sex chromosomes" since it is their combination that determines an individual's sex.  Thus, the genetic notation or nomemclature to describe the average woman with all 46 chromosomes, two of each of chromosomes 1 through 22 (the autosomes) and two chromosome x's is, "46xx". And, the notation for the average male with a complete set of 46 chromosomes, two of each of chromosomes 1 through 22 and one x chromosome and one y chromosome is, "46xy".