The term 'BRO OR SIS, E.G.' is an abbreviation for 'brother or sister, for example'. This term is used to refer to a SIBLING, which is someone who shares the same parents as another person. The crossword solutions for this term are REL (3 letters) and SIB (3 letters). REL stands for 'RELATIVE', which is a broad term that includes siblings, while SIB stands for 'SIBLING', which is a more specific term for a brother or sister.