(1):
(n.) An acknowledgment intended as an atonement for some improper or injurious remark or act; an admission to another of a wrong or discourtesy done him, accompanied by an expression of regret.
(2):
(n.) Something said or written in defense or justification of what appears to others wrong, or of what may be liable to disapprobation; justification; as, Tertullian's Apology for Christianity.
(3):
(n.) Anything provided as a substitute; a makeshift.
(4):
(v. i.) To offer an apology.