<p><strong>Noun</strong></p><ul><li>Any of numerous freshwater, marine, or parasitic one-celled protozoa of the order Amoebida, characterized by a granular nucleus surrounded by a jellylike mass of cytoplasm that forms temporary extensions, or pseudopodia, by which the organism moves, engulfs food particles, and forms food vacuoles.</li><li>A protozoan of the genus Amoeba, inhabiting bottom vegetation of freshwater ponds and streams: used widely in laboratory studies.</li></ul>