Hypo meaning : Melancholy; a fit of ‘hypochondria’; a morbid depression. A hypochondriac. Sodium thiosulphate, a photographic fixing agent. A hypoglycaemia attack in a person with diabetes. The substance sodium hyposulfite. A hypodermic syringe. Hypothecation. (in the study of law) A hypothetical case. A hypomelanistic snake.