Webster’s Revised Unabridged Dictionary · 1913
Hypo
Hy′po (hī′pō), n. Hypochondria. [Colloq.]
Hy′po, n. [Abbrev. from hyposulphite.] (Photog.) Sodium hyposulphite, or thiosulphate, a solution of which is used as a bath to wash out the unchanged silver salts in a picture. [Colloq.]