The term "homologous chromosomes" refers to
a pair of chromosomes with similar sequences.
In a cell, the chromosomes are in two sets: one of which is derived from the mother and the other from the father. The chromosomes that have the similar gene sequences or homologous chromosomes are paired during meiosis. This pairing is called synapsis.
A human cell contains 23 pairs of homologous chromosomes: 22 of them are homologous non-sex chromosomes (or autosomes) and 1 pair of sex chromosomes. In females, the homologous sex chromosomes are 2 X’s; in males the sex chromosomes are heterologous and they are X and Y chromosomes.