Quote Originally Posted by konny
And Roman citizens cannot be Roman mercenaries (or if you like, payed professional soldiers of the Roman army)? BTW, I didn't know that only citizens were allowed to serve in the professional Legions in our time frame.
AFAIK the general rule was that the legions were for Roman citizens only; others could join the auxilia and gain citizenship that way.

And the definition of a mercenary is someone who goes to war in the armed forces of another nation, for profit. I suppose you might also regard someone who fights for his own nation but outside the regular army (and with profit as the main motive) as a mercenary. But that isn't the case with the Roman legion.