1.  weakening(n = noun.event) - becoming weaker;
is a kind of shift, transformation, transmutation
has particulars: debilitation, enervation, enfeeblement, exhaustion, atrophy, withering, attenuation, fading, downfall, fall, loosening, relaxation, slackening
Antonym: strengthening
Derived form verb weaken₂

2.  weakening(n = noun.act) - the act of reducing the strength of something;
is a kind of decrease, diminution, reduction, step-down
has particulars: wilt, wilting, dilution, etiolation
Antonym: strengthening
Derived form verb weaken₁

1.  weakening(s = adj.all) debilitative, enervating, enfeebling - causing debilitation;

2.  weakening(s = adj.all) - moderating by making pain or sorrow weaker;