Nitric oxide (NO) Nitric oxide (NO), colourless, toxic gas that is formed by the oxidation of nitrogen. Though it has few industrial applications, nitric oxide performs important chemical signaling functions in humans and other animals and has various applications in medicine.
or British mollusc /ËmÉËlÉsk/. plural mollusks. Learner's definition of MOLLUSK. [count] biology. : any one of a large group of animals (such as snails and clams) that have a soft body without a backbone and that usually live in a shell.
snails, clams, squids and octopodes. Mollusca. Mollusks are a large group of invertebrate animals. Mollusks have soft bodies, and their bodies are not divided into rings like the segmented worms called annelids.