It's a "broken, swan's neck pediment" off of a highboy cabinet, since it has returns (side legs). It can also be said to have a central keystone-shaped plinth surmounted by an urn finial.
Casey

I agree....if you need verification.
Linda C

I thought that a pediment was the molding and trim that is sometimes found at the top of a window. Is that a pediment as well? Thanks for your help.

A pediment is an architectural term for an element that is or is similar to the gable end of a roof. A portico can have a pedimented gable. When a pediment does not run up to meet at a peak, it is a broken pediment (it was like that when I got here..) Swan's neck, as in your case, refers to the s-curvature of the raking parts.
A bit of trim over a door or window that runs horizontally is called an architrave. When it is peaked, it could be called a pedimented architrave, or if very elaborate on its own, a pediment.
There being a hierarchy to elements in classical architecture, an architrave is subservient to a pediment.
Casey, specialist in boring explanations

Thanks for the education. I was getting ready to go to a bookstore this weekend to try to get this figured out.