Cryogenic describes things that belong to the scientific study and use of very, very low temperatures — far colder than a kitchen freezer. Cryogenic tanks hold liquid nitrogen or liquid oxygen. Cryogenic engines, cryogenic storage, cryogenic freezing: the word tells you the thing works in that extreme cold, or was made by that science. The study itself is often called cryogenics, with an s; cryogenic, no s, is the describing word. Though actually, people stretch it. News stories say cryogenic freezing when they mean freezing a dead body in the hope of waking it later. Scientists more often call that cryonics, which is a different and much more doubtful idea. In careful talk, cryogenic just means of or using that deep cold, or belonging to that study, not bringing the dead back. You will meet it in science, engineering, and hospital talk about storing cells and blood.