From Citizendium, the Citizens' Compendium
- Life : Living systems, of which biologists seek the commonalities distinguishing them from nonliving systems.
- Organism : An individual living individual: a complex, adaptive physical system that acts a integrated unit that sustains metabolism and reproduces progeny that resemble it.
- Eukaryote : An organism that is composed of one or more cells containing cell nuclei.
- Kingdom (biology) : The second highest level taxon of organisms in scientific classification and biological taxonomy.
- : One of a loose group of sedentary, aquatic, filter-feeding invertebrate animals with soft and porous bodies, placed into the phylum Porifera.
- Metazoan : Any animal other than the sponges.
- : A clade of animals, all of which are bilaterally symmetrical during at least one point of their lives.
- Protostome : Add brief definition or description
- Ecdysozoan : Add brief definition or description
- Insect : One of numerous small arthropod animals with six legs, an exoskeleton that grows by molting, and oftentimes wings.
- Lophotrochozoan : Add brief definition or description
- Mollusk : Add brief definition or description
- Deuterostome : Superphylum of animals, and a subtaxon of the Bilateria branch of the subregnum Eumetazoa, which are distinguished by their unique embryonic development.
- Chordate : An animal who had a notochord — a stiff cord with nerve fibre bundles — somewhen during its life.
- Vertebrate : An animal who has a skeleton with a backbone, vertebrae, and/or a cranium.
- : An animal who dois not have a skeleton with a backbone, vertebrae, or a cranium.
- Plant (organism) : A eukaryotic organism, grouped into the kingdom Plantae, that typically synthesizes nutrients through photosynthesis and possesses the inability to voluntarily move.
- Fungus : A eukaryotic organism, classified into the kingdom Fungi, that is heterotrophic and digest their food externally, and may be a yeast, mold, or mushroom.
- Protist : A unicellular organism grouped into the kingdom Protista that may have characteristics of plants and/or animals.
- Bacteria : A major group of single-celled microorganisms.
- Archaea : A major group of numerous microorganisms fundamentally different from the bacteria and including many chemolithotrophs and extremophiles.