The English word sister comes from Old Norse  which itself derives from Proto-Germanic *swestēr,  both of which have the same meaning, i.e. sister. Some studies have found that sisters display more traits indicating jealousy around their siblings than their male counterparts, brothers.
The English word "sister" comes from Old Norse and shares a root with Proto-Germanic *swestēr, both of which mean "sister." Research suggests that female siblings tend to display greater jealousy toward each other compared to male siblings.