'To tone down' definitions:

Definition of 'To tone down'

From: GCIDE

Tone \Tone\, v. t. [imp. & p. p. Toned; p. pr. & vb. n. Toning.]
1. To utter with an affected tone. [1913 Webster]
2. To give tone, or a particular tone, to; to tune. See Tune, v. t. [1913 Webster]
3. (Photog.) To bring, as a print, to a certain required shade of color, as by chemical treatment. [1913 Webster]
To tone down. (a) To cause to give lower tone or sound; to give a lower tone to. (b) (Paint.) To modify, as color, by making it less brilliant or less crude; to modify, as a composition of color, by making it more harmonius. [1913 Webster]
Its thousand hues toned down harmoniusly. --C. Kingsley. [1913 Webster] (c) Fig.: To moderate or relax; to diminish or weaken the striking characteristics of; to soften. [1913 Webster]
The best method for the purpose in hand was to employ some one of a character and position suited to get possession of their confidence, and then use it to tone down their religious strictures. --Palfrey. [1913 Webster]
To tone up, to cause to give a higher tone or sound; to give a higher tone to; to make more intense; to heighten; to strengthen. [1913 Webster]