firstborn

noun

The oldest child in a family; the one born before any brothers or sisters.

Example sentence

“As the firstborn, she often looked after her younger brothers.”

Slightly formal or biblical in flavor; in conversation people usually say 'oldest child'. Often used with a possessive: 'their firstborn'.

Related words

newbornA baby that has just been born.inlawA person who is under the protection of the law rather than outside it.babyA very young child, from birth until around the time it learns to walk.godparentSomeone who promises at a child's baptism or naming ceremony to help raise the child, traditionally in matters of faith.kidA child or young person; informally, it can also refer to a young adult.goddaughterA girl for whom a godparent takes responsibility at her baptism.