apologetic

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

• adjective Offering or expressing an apology or excuse.
• adjective Self-deprecating; humble.
• adjective Serving as or containing a formal justification or defense.
• noun A formal defense or apology.

from The Century Dictionary.

• Of, pertaining to, or containing a defense; defending by words or arguments; said or written in defense: as, an apologetic essay.
• Making apology or excuse; manifesting regret for or excusing some fault, failure, deficiency, imperfection, etc., in one's own conduct or that of another: as, an apologetic reply; an apologetic manner.
• noun An apology; a defense.

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

• adjective Defending by words or arguments; said or written in defense, or by way of apology; regretfully excusing.

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

• adjective Having the character of apology; regretfully excusing
• adjective dated Defending by words or arguments; said or written in defense.

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

• adjective offering or expressing apology