chlorous

from The Century Dictionary.

• Pertaining to or containing chlorin; specifically, containing chlorin in larger proportion than chloric compounds: as, chlorous oxid; chlorous acid.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Of, pertaining to, or derived from, chlorine; -- said of those compounds of chlorine in which this element has a valence of three, the next lower than in chloric compounds.
• adjective (Chem. Physics), obsolete Pertaining to, or resembling, the electro-negative character of chlorine; hence, electro-negative; -- opposed to basylous or zincous.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective chemistry Of a compound, containing chlorine with a lower oxidation number than equivalent chloric compounds; especially having an oxidation number of 3.
• adjective obsolete Relating to, or resembling, the electronegative character of chlorine; hence, electronegative; opposed to basylous or zincous.