Is it ensure, insure, or assure?
organism or·gan·ism (ôr'gə-nĭz'əm)
An individual form of life, such as a plant, an animal, a bacterium, a protist, or a fungus; a body made up of organs, organelles, or other parts that work together to carry on the various processes of life.
An individual form of life that is capable of growing, metabolizing nutrients, and usually reproducing. Organisms can be unicellular or multicellular. They are scientifically divided into five different groups (called kingdoms) that include prokaryotes, protists, fungi, plants, and animals, and that are further subdivided based on common ancestry and homology of anatomic and molecular structures.