| genus anatotitan | (n) genus of large duck-billed dinosaurs; late Cretaceous |
| anabas | (n) the type genus of the family Anabantidae; small fish that resemble perch, Syn. genus Anabas |
| anabrus | (n) a genus of Tettigoniidae, Syn. genus Anabrus |
| anacardium | (n) type genus of the Anacardiaceae: cashew, Syn. genus Anacardium |
| anacyclus | (n) a Spanish pellitory, Syn. genus Anacyclus |
| anadenanthera | (n) 2 species of tropical American shrubs or trees, Syn. genus Anadenanthera |
| anagallis | (n) chiefly Old World herbs, Syn. genus Anagallis |
| anagasta | (n) moth whose larvae are flour moths, Syn. genus Anagasta |
| anagyris | (n) very small genus of shrubs of southern Europe having backward curving seed pods, Syn. genus Anagyris |
| ananas | (n) a genus of tropical American plants have sword-shaped leaves and a fleshy compound fruits composed of the fruits of several flowers (such as pineapples), Syn. genus Ananas |
| anaphalis | (n) a genus of herbs of north temperate regions having hoary leaves: pearly everlasting, Syn. genus Anaphalis |
| anarhichas | (n) type genus of the Anarhichadidae, Syn. genus Anarhichas |
| anas | (n) type genus of the Anatidae: freshwater ducks, Syn. genus Anas |
| anasa | (n) squash bugs, Syn. genus Anasa |
| anastatica | (n) one species: rose of Jericho; resurrection plant, Syn. genus Anastatica |
| anastomus | (n) openbills, Syn. genus Anastomus |