The term "uterine brother" is used to refer to a brother who shares the same mother but not the same father. However, there are several other synonyms that can be used to describe this relationship. Some common alternatives include "maternal half-brother," "half-brother through the mother," "mother's son from different father," and "half-sibling through the mother's side." Each of these terms adequately describes the relationship between siblings who share a biological mother but have different biological fathers. It is important to note that while these terms may differ, they all refer to the same relationship and should be used interchangeably.