The process of declining or sinking to a weaker or inferior condition; gradual loss of force, vigour, vitality, or excellence of quality; falling…

The action of fade, v.1

Impairment, abatement.

Falling off, decay, decreasing, waning, etc.; = decline, n. 1.

The action or process of disappearing, declining, etc.

figurative. Chiefly with reference to the period of a person's late maturity (cf. autumn, n. 3).

figurative. Inclination; declension, decline.

figurative. With reference to a thing: decline, decay, loss of vitality or vigour.

Falling off (in quantity, volume, intensity, etc.); dwindling, decrease. Obsolete.

Diminution suffered or sustained; falling off. archaic.

The act or process of diminishing in strength, vigour, etc.; decline; deterioration.

†(a) Music (apparently) an imperfect cadence, a half close (obsolete rare); (b) a decline, a diminution, a reduction (cf. falling off, n. 2); (c) P…

spec. Decrease, diminution, deterioration. Frequently as a count noun.

A falling off, a diminution, a reduction.

A decline or downward trend (esp. as part of a cycle of fluctuation); a downturn.