This is the 609th most frequent Spanish word.
duelo
"Duelo" means "mourning" or "grief" and can also mean "duel" depending on the context.
In this sentence, 'duelo' is used to represent the emotional state of mourning or grieving a loss.
Estoy en duelo por la pérdida de mi mascota.
I am in mourning for the loss of my pet.
Here, 'duelo' refers to a formal combat to settle a dispute, usually historical.
Los caballeros resolvieron su disputa con un duelo al amanecer.
The gentlemen resolved their dispute with a duel at dawn.
In this case, 'duelo' is used in a figurative sense to describe a sporting or competitive confrontation.