The Gruiformes are an order containing a considerable number of living and extinct bird families, with a widespread geographical diversity. Gruiform means "crane-like".
Traditionally, a number of wading and terrestrial bird families that did not seem to belong to any other order were classified together as Gruiformes. These include 14 species of large cranes, about 145 species of smaller crakes and rails, as well as a variety of families comprising one to three species, such as the Heliornithidae, the limpkin, or the trumpeters. Other birds have been placed in this order more out of necessity to place them somewhere; this has caused the expanded Gruiformes to lack distinctive apomorphies. Recent studies indicate that these "odd Gruiformes" are if at all only loosely related to the cranes, rails, and relatives ("core Gruiformes").
The Collaborative International Dictionary
Gruiformes \Gruiformes\ n. An order of inland marsh-dwelling birds with long legs and necks and bills that wade in water in search of food, including cranes, rails, and bustards.
Syn: order Gruiformes.