exculpate, absolve, exonerate, acquit, vindicate mean to free from a charge.

exculpate implies a clearing from blame or fault often in a matter of small importance.

absolve implies a release either from an obligation that binds the conscience or from the consequences of disobeying the law or committing a sin.

exonerate implies a complete clearance from an accusation or charge and from any attendant suspicion of blame or guilt.

acquit implies a formal decision in one's favor with respect to a definite charge.

vindicate may refer to things as well as persons that have been subjected to critical attack or imputation of guilt, weakness, or folly, and implies a clearing effected by proving the unfairness of such criticism or blame.

maintain, assert, defend, vindicate, justify mean to uphold as true, right, just, or reasonable.

maintain stresses firmness of conviction.

assert suggests determination to make others accept one's claim.

defend implies maintaining in the face of attack or criticism.

vindicate implies successfully defending.

justify implies showing to be true, just, or valid by appeal to a standard or to precedent.