D defs.my
Entry 2 senses Webster, 1913

Hypo-

· Hy·po- · IPA /ˈhaɪpoʊ/
01 A prefix signifying a less quantity, or a low state or degree, of that denoted by the word with which it is joined, or position under or beneath.
  1. 1.
    A prefix signifying a less quantity, or a low state or degree, of that denoted by the word with which it is joined, or position under or beneath.
  2. 2.
    A prefix denoting that the element to the name of which it is prefixed enters with a low valence, or in a low state of oxidization, usually the lowest, into the compounds indicated; as, hyposulphurous acid.(Chem.)