condone, pardon, apologise, apologize, alibi, justify, relieve, explain, let off, beg off, more...

blame, accuse, charge, condemn, criticize

good, only, sufficient, reasonable, valid, plausible, poor, little, convenient, lame, legitimate

another reason,   a reason,   spare me,   to justify,   explain oneself,   an out,   fail to justify,   plea in mitigation,   give leave,   to explain away