1. loss of sensation with or without loss of consciousness
The patient was given intravenous medication to induce anesthesia. … doctors freeze the tumor with little coils filled with liquid nitrogen that are inserted in the prostate under anesthesia.
— Andy Grove Awareness during anesthesia is a serious complication with potential long-term psychological consequences.
— Michael S. Avidan et al. We often radiograph dogs when they are under anesthesia for spaying or neutering or other routine procedures.
— Bonnie Wilcox — see also general anesthesia, local anesthesia

2. an agent that produces anesthesia anesthetic
A capnometer measures the amount of carbon dioxide in exhaled air, thereby insuring that the tubes bringing oxygen and anesthesia to the patient are properly placed.
— Lisa Belkin She was still groggy from her anesthesia, and she had an I.V. tube in her arm.
— The New Yorker These substances [=endorphins], which have been identified in recent years through research on brain chemistry, act as a natural anesthesia that can lessen extreme pain.
— Norman Cousins

3. loss of feeling in a person's body or part of the body through the use of drugs

4. loss of feeling in all or part of the body with or without loss of consciousness The patient was given an injection before surgery to produce anesthesia.

5. loss of sensation with or without loss of consciousness that is artificially produced by the administration of one or more agents that block the passage of pain impulses along nerve pathways to the brain
… doctors freeze the tumor with little coils filled with liquid nitrogen that are inserted in the prostate under anesthesia.
— Andy Grove Awareness during anesthesia is a serious complication with potential long-term psychological consequences.
— Michael S. Avidan et al. — see general anesthesia, local anesthesia

6. loss of sensation especially to touch usually resulting from injury or disease

7. an agent that produces anesthesia anesthetic
During surgery, you will be given some form of anesthesia, which are medicines given to relieve pain and sensation during surgery.
— HopkinsMedicine.org A capnometer measures the amount of carbon dioxide in exhaled air, thereby insuring that the tubes bringing oxygen and anesthesia to the patient are properly placed.
— Lisa Belkin