FLAT (4)

Flat (?), v. t. [imp. & p. p. Flatted (?); p. pr. & vb. n. Flatting (?).] 1. 1. To make flat; to flatten; to level.
2. 2. To render dull, insipid, or spiritless; to depress.
Passions are allayed, appetites are flatted. Barrow. 3. 3. To depress in tone, as a musical note; especially, to lower in pitch by half a tone.