Simply, a cyborg is a successful augmentation of a species to make it outperform its peers. That crazy character from the movie Robocop is a cyborg. A mixture of flesh and machine.
Usually, cyborg modifications are permanent, they should last the rest of the duration of the being that is modified.
Cyborgs don't just have to be human, they can be cats, dogs, fish, or even Cyrans. A natural born Cyran is not considered a cyborg because even though it has metal and blades in its body, it is naturally that way, no modifications are made to the Cyran to make them that way. Cyrans can be cybernated though. Armex, on the other hand, are born without cybernations or modifications, they are doctored up from birth to be a co-mix of machinery and flesh.