Hypochlorous \Hy`po*chlo"rous\, a. [Pref. hypo- + chlorous.] (Chem.) Pertaining to, or derived from, chlorine having a valence lower than in chlorous compounds. {Hypochlorous acid} (Chem.), an acid derived from chlorine, not known in a pure state, but forming various salts, called hypochlorites.