oximeter

/ɑkˈsɪmɪtər/
noun
  1. A medical device that measures the amount of oxygen in a person's blood, usually clipped onto a finger or earlobe.
    • The nurse placed an oximeter on my finger to check my oxygen level.
    • The doctor used an oximeter to see if the patient needed extra oxygen.
    • Many people bought an oximeter to monitor their health at home during the pandemic.