responsible

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Liable to be required to give account, as of one's actions or of the discharge of a duty or trust.
• adjective Required to render account; answerable.
• adjective Involving important duties, the supervision of others, or the ability to make decisions with little supervision.
• adjective Being a source or cause.
• adjective Able to make moral or rational decisions on one's own and therefore answerable for one's behavior.
• adjective Able to be trusted or depended upon; trustworthy or reliable.
• adjective Based on or characterized by good judgment or sound thinking.

from The Century Dictionary.

• Correspondent; answering; responsive.
• Answerable, as for an act performed or for its consequences, or for a trust reposed or a debt; accountable; specifically, in ethics, in general, having such a mental or moral character as to be capable of knowing and observing the distinction of right from wrong in conduct, and therefore morally accountable for one's acts; in particular (with reference to a certain act), acting or having acted as a free agent, and with knowledge of the ethical character of the act or of its consequences.
• Able to answer or respond to any reasonable claim or to what is expected; able to discharge an obligation, or having estate adequate to the payment of a debt.
• Involving responsibility.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Liable to respond; likely to be called upon to answer; accountable; answerable; amenable.
• adjective Able to respond or answer for one's conduct and obligations; trustworthy, financially or otherwise.
• adjective Involving responsibility; involving a degree of accountability on the part of the person concerned.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Answerable for an act performed or for its consequences; accountable; amenable, especially legally or politically.
• adjective Capable of responding to any reasonable claim; able to answer reasonably for one's conduct and obligations; capable of rational conduct.
• adjective Involving responsibility; involving a degree of personal accountability on the part of the person concerned.
• adjective Being a primary cause or agent of some event or action; capable of being credited for something, or of being held liable for something.
• adjective Able to be trusted; reliable; trustworthy.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective being the agent or cause
• adjective worthy of or requiring responsibility or trust; or held accountable
• adjective having an acceptable credit rating