According to: The American College Dictionary: fin'-ee-el,
noun, Architecture. a. an ornamental termination of a pinnacle,
gable, etc., usually foliated.
b. a vertical termination; a cast, carved, or turned ornament capping another form.
A finial is much more than a decoration, it is also a way to weather proof and protect the apex of a tower, turret, cupola or gazebo. Finials have been an integral part of many architectural periods including Medieval, Tudor, Gothic Revival, Italianate, all the Victorian styles, Richardsonian Romanesque, Chateauesque and Second Empire. The current Victorian Revival has renewed an interest in these delightful adornments.
A basic ball and point finial is appropriate for all styles of architecture.
This fancy finial resembles a "bouquet" high on a roof.