To weaken the brilliancy of (colour); to make of a faint or washed-out hue.

transitive. To soften, to subdue or tone down, to free from harshness or crudity. Also: to make (a person) softer or more tolerant in nature; to…

Of colours: To modify a colour by mixing it with some other colour. Also to break down 5 at phrasal verbs, and broken colours (see broken, adj.).

transitive. Chiefly Dyeing and Calico-printing. To tone down (colours) by the application of additives. Now rare.

To render less glaring or conspicuous.

To lower or reduce in price, strength, purity, etc.; to reduce or tone down in colour (cf. degradation, n.2).

transitive. To deprive of its intensity; to make less intense.

transferred of natural effects.