Bible Dictionary
SISTER
A sister is a female blood relative, half-sister, or female member of a family or clan. Scripture also uses the term figuratively for fellow believers, related kingdoms or cities, paired objects, and a beloved bride.
Biblical Usage
The New Testament uses “sister” for physical kinship and for female fellow-members in Christ. The Old Testament also applies it to Israel and Judah, related cities, paired curtains or wings, wisdom, and a spouse as a term of endearment.