Red-billed quelea closely related to the fodies ("Foudia"), a genus of six or seven species that occur on the islands of the western Indian Ocean. These two genera are in turn the sister clade to the Asian species of the genus "Ploceus". The following tree represents current insight of the relationships between the species of "Quelea", and their closest relatives. Interbreeding between red-billed and red-headed queleas has been observed in captivity. The red-billed quelea is a small sparrow-like bird, approximately long and weighing , with a heavy, cone-shaped bill, which is red (in females outside the breeding season and males) or orange
Red-billed quelea "aethiopica". Linnaeus himself did not explain the name "quelea". "Quelea quelea" is locally called "kwelea domo-jekundu" in Swahili, "enzunge" in Kwangali, "chimokoto" in Shona, "inyonyane" in Siswati, "thaha" in Sesotho and "ndzheyana" in the Tsonga language. M.W. Jeffreys suggested that the term came from medieval Latin "qualea", meaning "quail", linking the prodigious numbers of queleas to the hordes of quail that fed the Israelites during the Exodus from Egypt. The subspecies "lathamii" is probably named in honor of the ornithologist John Latham. The name of the subspecies "aethiopica" refers to Ethiopia, and its type was collected in the neighbouring Sennar