one of a pair of babies from different eggs that a woman gives birth to at the same time. Two babies born from a single egg look exactly like each other and are called identical twins.

half brother (noun)

a brother who has either the same mother or the same father as you

half sister (noun)

a sister who has either the same mother or the same father as you

identical twin (noun)

one of a pair of babies that a woman gives birth to at the same time that look exactly like each other because they have developed from a single egg

kid (adjective)

informal your kid brother or sister is your younger brother or sister

kuya (noun)

Philippine English an older brother

middle child/daughter/brother etc. ()

the child, daughter, brother, etc. who is between the oldest and the youngest in age

Siamese twin (noun)

old-fashioned one of two people born with their bodies joined together. This is now considered offensive and it is more polite to say conjoined twin.

sibling (noun)

formal your siblings are your brothers and sisters

sibling rivalry (noun)

competition between brothers and sisters, often for their parents’ attention

sis (noun)

informal an informal word used for talking to or about your sister

sister (noun)

a daughter of your parents. A son of your parents is called your brother

sisterly (adjective)

appropriate for a sister, or typical of a sister

someone’s little brother/sister ()

someone’s younger brother/sister

twin (noun)

one of two children born at the same time to the same mother. Twins of the same sex who look exactly like each other are called identical twins. Twins that are not identical are called fraternal twins