Eldest
Part of speech: adjective
Definition: Most old; greatest in age or seniority.
Example sentence: I am the eldest child; it's lonely at the top.
First
Part of speech: adjective
Definition: Having no predecessor. The ordinal number corresponding to one.
Part of speech: adverb
Definition: Before anything else; firstly.
Part of speech: noun
Definition: The person or thing in the first position.The first gear of an engine.Something that has never happened before; a new occurrence.first baseA first-class honours degree.A first-edition copy of some publication.
Example sentence: Victorious warriors win first and then go to war, while defeated warriors go to war first and then seek to win.