Vulnerable

vul-ner-a-ble (vul′nərəbəl)

adjective
1. In a state of being easily wounded.
After telling him how she felt about him and spending the night trekking through the icy weather, she felt both vulnerable to heartache and vulnerable to catching a cold.
2. Easily and, possibly, very dramatically swayed, emotionally or psychologically.
Having spent so much time alone, in his cabin in the woods, pondering the various turns his life had taken, our hero was vulnerable to suggestion. His mother, a strange man on the street or anyone could tell him anything and he would internalize it, think about it long and hard, then change the course of his life accordingly.
3. Difficult to defend.
A castle in a valley would be as vulnerable to attack as the perceived masculinity of a man who readily shows his own vulnerability. Yet, some castles should be easier to attack. The confidence that a castle built in a valley must have in making itself so vulnerable to attack would have to come from something that can't be beaten out by force. And so, I will concede to praise Alanis Morissette's vulnerable man.

Synonyms:* accessible, assailable, chancy, defenseless, delicate, exposed, humble, insecure, liable, loaded, menaced, naked, precarious, ready,rosky, sensitive, shaky, speculative, sucker, susceptible, tender, thin-skinned, touchy, unguarded, unprotected, unsafe, unstable, weak, wide-open.

* Because being vulnerable is the topic of so much poetry I think the synonyms are basically interchangeable with the definitions. For instance, imagine the castle in the valley as naked and shaky.