Definition of eldest in US English:

eldest

adjective

  • (of one out of a group of related or otherwise associated people) of the greatest age; oldest.

    ‘Swift left the company to his eldest son, Charles’
    ‘he was the eldest of the three’
    • ‘Their parents' expectations may be very high and the eldest child may have the most expected from them.’
    • ‘Former South African president Nelson Mandela has revealed that his eldest son has died of Aids.’
    oldest, first, firstborn, most grown up, big, biggest
    View synonyms

Origin

Old English ieldest, eldest, of Germanic origin; related to German ältest, also to eld and old.

Pronunciation

eldest

/ˈeldəst//ˈɛldəst/