Eldest and Worn-out

Eldest adjective - First in order of birth.

Worn-out and eldest are semantically related. In some cases you can use "Worn-out" instead an adjective "Eldest". obsolete substitute

Worn-out adjective - Depleted in strength, energy, or freshness.

Eldest and worn-out are semantically related. Sometimes you can replace term "Eldest" with "Worn-out", this terms are similar.