Flightless bird Flightless bird Flightless birds are birds that through evolution lost the ability to fly. There are over 60 extant species including the well known ratites (ostrich, emu, cassowary, rhea and kiwi) and penguins. The smallest flightless bird is the Inaccessible Island rail (length 12.5 cm, weight 34.7 g). The largest (both heaviest and tallest) flightless bird, which is also the largest living bird, is the ostrich (2.7 m, 156 kg). Ostriches are farmed for their decorative feathers, meat and their skins, which are used to make leather. Many domesticated birds, such as the domestic chicken and domestic duck, have lost
Four-letter word category includes words that are euphemistic evasions of "stronger" words, as well as those that happen to be short and have both an expletive sound to some listeners as well as a sexual or excretory meaning (many also have other, non-vulgar meanings): "" (US), "", "", "" (US), "" (UK, NZ, AUS), "" and "", as several examples. Finally, certain four-lettered terms with limited usage can be considered offensive by some, within the regional dialect in which they are used, such as "" and "mary". Occasionally the phrase "four-letter word" is humorously used to describe common words composed of four