2. To throw down; to bring to the ground; to prostrate;
hence, to depress; to deject; to dispirit.
3. To make vapid or insipid; to render stale.
4. (Mus.) To lower the pitch of; to cause to sound less
sharp; to let fall from the pitch.
{To flatten a sail} (Naut.), to set it more nearly
fore-and-aft of the vessel.
{Flattening oven}, in glass making, a heated chamber in which
split glass cylinders are flattened for window glass.