Posted in Web Ostrich | Definition of Ostrich by Merriam-Webster May 20, 2019 Ostrich definition is – a swift-footed 2-toed flightless ratite bird (Struthio camelus) of Africa that is the largest of existing birds and often weighs 300 pounds (140 kilograms). : https://www.merriam-webster.com/dictionary/ostrich