eldest
n. countablen. the person in a family or group who was born first. You use this to talk about the oldest child among siblings.
n. the first-born member of a family or group. Often used as a substantive noun to refer to the person with the greatest age among siblings.
As the eldest, she often looked after her younger brothers.
The inheritance was traditionally passed down to the eldest, though modern laws have changed these family customs.
While the younger children were free to pursue artistic careers, the eldest felt a heavy burden of responsibility to manage the family's struggling farm.
Usually preceded by the definite article 'the'.
He is the eldest than meHe is older than meEldest is a superlative form used for groups of three or more; it cannot be used in comparative 'than' structures.