The term 'kiwi or ostrich' can be summarized by the word 'RATITE, ' which is a six-letter word that refers to a group of flightless birds. This group includes the kiwi and the ostrich, as well as other species such as the emu, rhea, and cassowary. Ratites are characterized by their flat breastbones, which lack the keel structure found in flying birds. They are also known for their large size and long legs.