gear: a mechanism for transmitting motion for some specific purpose (as the steering gear of a vehicle)
object: a tangible and visible entity; an entity that can cast a shadow
polypodiaceae: ferns: a large family that in some classification systems has been subdivided into several families (including Aspleniaceae and Blechnaceae and Davalliaceae and Dennstaedtiaceae and Dryopteridaceae and Oleandraceae and Pteridaceae)