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Chloro- is a combining form used like a prefix that can mean “green” or indicate the chemical element chlorine. It is used in many medical and scientific terms, especially in biology and chemistry.

Chloro- comes from the Greek �����ō��ó��, meaning “light green” or “greenish yellow.” Chlorine is so named because the gas has a pale green color.

Chloro- is a variant of chlor-, as in chloranil, used when combined with words or word elements beginning with a consonant. However, in chemistry, chlor- is also often combined to words or word elements beginning with consonants.

Want to know more? Read our 51�Թ�s That Use chlor– article.

A word you are likely familiar with that features chloro- is chlorophyll, “the green coloring matter of leaves and plants.”

As we know, the first part of the word, chloro-, means “green.” The second part of the word, –phyll, means “leaf,” from the Greek ���ý�����Dz�. The word chlorophyll, then, literally translates to “green leaf.” How sensible!

What are some words that use the combining form chloro-?

• chloroacetic
• chlorobenzene
• chlorocarbon
• chlorohydrin
• chloronaphthalene
• chloroplast
• chloropsia
• chlorothiazide

What are some other forms that chloro- may be commonly confused with?

• cholo-
• chiro-
• chorio-
• chrom-
• chylo-
• colo-

What elements do chemical compounds known as chlorocarbons always contain?