Image borrowed from : http://www.lampfinials.com/
I was unscrewing the metal piece that holds a lampshade in place in order to change the lampshade. My sister commented that I could also change out the finial if I wanted to. She had worked in a department store in housewares and said that it can also refer to the decorative ends of curtain rods. Apparently this may be a familiar word to people in decorating.
Definition of FINIAL
1: a usually foliated ornament forming an upper extremity especially in Gothic architecture
2: a crowning ornament or detail (as a decorative knob)
Origin of FINIAL
Middle English, from final, finial final
First Known Use: 15th century