Incapable of being overcome or surmounted.
Not usable as legal tender.
Incapable of being passed over, crossed, or negotiated.
Open to disclosing one's inner thoughts and feelings, acting in spite of one's instinct to self-preservation.
More likely to be exposed to malicious programs or viruses.
More or most likely to be exposed to the chance of being attacked or harmed, either physically or emotionally.