Oxygenation is the name of the act, the process, or the state of adding oxygen — or of already holding enough of it. If a doctor talks about a patient’s oxygenation, they mean how well the blood is carrying oxygen, often shown as a number from a small clip on a finger. Poor oxygenation means the body is not getting enough. In a lab or a fish farm, oxygenation of water means putting oxygen into the water. The word sits beside the verb oxygenate: you oxygenate, and that oxygenation is what happened, or how good the oxygen level is. It is medical and scientific. You will rarely hear it in a café or a storybook.