What does chloride mean?
A chloride is a chemical compound in which the element chlorine is bonded to another element or group — sodium chloride, ordinary table salt, being by far the most familiar example. The term also denotes the chloride ion (Cl⁻), the negatively charged form of chlorine that dissolves readily in water and plays a vital role in living systems. In human physiology, chloride is one of the body's principal electrolytes, helping regulate fluid balance, blood acidity, and nerve signalling, which is why its concentration is routinely reported in blood test results. Chemists encounter chlorides constantly: hydrogen chloride forms hydrochloric acid when dissolved in water, calcium chloride de-ices roads, and polyvinyl chloride (PVC) is among the world's most widely used plastics. Though chiefly technical in register, the word appears in everyday contexts wherever salt, water chemistry, or materials are discussed, making it a quietly essential term bridging the kitchen, the laboratory, and the clinic.
nounA compound of chlorine with another element or group, especially a binary compound such as sodium chloride. In physiology, chloride refers to the chloride ion (Cl⁻), an essential electrolyte in blood and body fluids.
- A chemical compound in which chlorine is bonded to another element or group, such as sodium chloride or hydrogen chloride.
- The chloride ion (Cl⁻), especially as an electrolyte present in blood, sweat, and other body fluids.
"Sodium chloride, better known as table salt, is the most familiar chloride in everyday life."
"Calcium chloride is often spread on roads to melt ice in winter."
"The blood test showed that his chloride levels were slightly below the normal range."
Plural used when discussing multiple distinct chloride compounds; rarely pluralized in physiological contexts.
"Organic chemists frequently work with alkyl chlorides in synthesis."
The chloride in your table salt is also coursing through your bloodstream right now — your nerves couldn't fire without it.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of chloride
The word 'chloride' derives from 'chlorine', coined in the early 19th century from the Greek 'chlōros', meaning pale green or yellowish-green, a reference to the gas's distinctive colour. The suffix '-ide' was adopted by chemists of that era to name binary compounds formed from their constituent elements. It thus belongs to a family of scientific terms built on the same Greek root, including chlorophyll ('green leaf') and chloroform.
How chloride is actually used
Primarily a technical term used in chemistry, medicine, and science writing; rarely encountered in casual conversation except in fixed compounds like sodium chloride. In medical contexts, 'chloride' usually refers specifically to the measured concentration of chloride ions in blood serum.
Easily confused with chloride
Chlorine is the chemical element itself (Cl₂, a toxic green gas), while a chloride is a compound containing chlorine combined with another element or the negatively charged Cl⁻ ion.
Chlorite is a different ion containing chlorine and oxygen (ClO₂⁻) or a green mineral, whereas chloride is simply the Cl⁻ ion with no oxygen.