What does bichloride mean?
Bichloride is an older chemical term for a compound in which two atoms of chlorine are bonded to another element — what modern chemistry calls a dichloride. The word is best known from the phrase "bichloride of mercury," the once-common name for mercuric chloride (HgCl₂), a highly toxic salt that nineteenth-century medicine used extensively as a disinfectant and antiseptic before safer agents replaced it. Formed with the Latin-derived prefix bi-, meaning "two," it belongs to a family of now-superseded names such as bicarbonate and bisulfate, many of which survive while bichloride has largely faded. Today the word appears mainly in historical accounts, old pharmacopoeias, and antique medical literature rather than in current scientific usage. Its connotations are clinical and period-specific: to encounter bichloride in text is usually to be reading about an earlier era of medicine or chemistry, when mercury compounds were routine household and hospital remedies despite their dangers.
nounA chemical compound containing two atoms of chlorine combined with another element or group; a dichloride. The term is now largely historical or technical, most famously in "bichloride of mercury" (mercuric chloride, HgCl₂).
- A chemical compound in which two atoms of chlorine are combined with another element or radical (now more usually called a dichloride).
- Especially in "bichloride of mercury": mercuric chloride (HgCl₂), historically used as an antiseptic and disinfectant.
"In the nineteenth century, dilute solutions of bichloride of mercury were widely used as a disinfectant in hospitals."
"Bichloride of mercury was once a staple of hospital disinfection routines."
"The old pharmacopoeia listed bichlorides alongside other metallic salts."
The plural is rare and appears mainly in general references to a class of such compounds in older chemical texts.
"The treatise catalogued various bichlorides of the heavy metals."
Before modern antiseptics, surgeons soaked their instruments and even their hands in "bichloride of mercury" — a poison so corrosive it was once sold under the name "corrosive sublimate."
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of bichloride
The word combines the Latin prefix bi-, meaning "two," with "chloride," itself derived from chlorine, the element named in the early nineteenth century from Greek chloros, meaning "pale green." It follows the same naming pattern as bicarbonate and bisulfate, coined when chemists described compounds by simple numerical prefixes. As systematic nomenclature took hold, such names were gradually replaced by terms like "dichloride," leaving bichloride chiefly in historical and pharmaceutical contexts.
How bichloride is actually used
The word is dated and chiefly encountered in historical, pharmaceutical, or older technical texts; modern chemistry prefers "dichloride." It carries no informal register and appears almost exclusively in writing rather than speech.
Easily confused with bichloride
"Dichloride" is the modern, systematic name for a compound with two chlorine atoms, while "bichloride" is an older prefix-based name for the same thing that survives chiefly in fixed historical phrases.
A monochloride contains one chlorine atom per molecule, whereas a bichloride contains two.