Capable of being vanquished; conquerable; subduable.

adjective. That may be vanquished.

adjective. That can be vanquished; defeatable, conquerable.

adjective. susceptible to being defeated

"He scorns all that are so silly to _trust_ [53] him, and only not scorns his enemy, especially if as bad as himself: he fears him as a man well armed and provided, but sets boldly on good natures, as the most vanquishable."

unvanquishable  

conquerable