chlorophyll

American  

[klawr-uh-fil, klohr-] / ˈklɔr ə fɪl, ˈkloʊr- /

Or chlorophyl

noun

Botany, Biochemistry.

1. the green coloring matter of leaves and plants, essential to the production of carbohydrates by photosynthesis, and occurring in a bluish-black form, C 55 H 72 MgN 4 O 5 chlorophyll a, and a dark-green form, C 55 H 70 MgN 4 O 6 chlorophyll b.

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chlorophyll British  

/ ˈklɔːrəfɪl /

noun

1. the green pigment of plants and photosynthetic algae and bacteria that traps the energy of sunlight for photosynthesis and exists in several forms, the most abundant being chlorophyll a (C 55 H 72 O 5 N 4 Mg): used as a colouring agent in medicines or food ( E140 )

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chlorophyll Scientific  

/ klôr′ə-fĭl /

1. Any of several green pigments found in photosynthetic organisms, such as plants, algae, and cyanobacteria. At its molecular core, chlorophyll has a porphyrin structure but contains a magnesium atom at its center and a long carbon side chain. Chlorophyll absorbs red and blue wavelengths of light, but reflects green. When it absorbs light energy, a chlorophyll molecule enters a higher energy state in which it easily gives up an electron to the first available electron-accepting molecule nearby. This electron moves through a chain of acceptors and is ultimately used in the synthesis of ATP, which provides chemical energy for plant metabolism. Plants rely on two forms of chlorophyll, chlorophyll a (C ₆₆ H ₇₂ MgN ₄ O ₅) and chlorophyll b (C ₆₆ H ₇₀ MgN ₄ O ₆), which have slightly different light absorbing properties. All plants, algae, and cyanobacteria have chlorophyll a, since only this compound can pass an electron to acceptors in oxygen-producing photosynthetic reactions. Chlorophyll b absorbs light energy that is then transferred to chlorophyll a. Several protist groups such as brown algae and diatoms lack chlorophyll b but have another pigment, chlorophyll c, instead. Other closely related pigments are used by various bacteria in photosynthetic reactions that do not produce oxygen.

2. See more at photosynthesis

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chlorophyll Cultural  

1. The complex chemical that gives a plant its green color and plays an important role in the conversion of sunlight into energy for the plant. (See photosynthesis.)

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Word History

From its name, one might think that chlorophyll has chlorine in it, but it doesn't. The chloro– of chlorophyll comes from the Greek word for “green”; chlorophyll in fact is the chemical compound that gives green plants their characteristic color. The name of the chemical element chlorine comes from the same root as the prefix chloro–, and is so called because it is a greenish-colored gas.

Other Word Forms

• chlorophylloid adjective
• chlorophyllous adjective

Etymology

Origin of chlorophyll

First recorded in 1810–20; chloro- ¹ + -phyll

Compare meaning

How does chlorophyll compare to similar and commonly confused words? Explore the most common comparisons:

• chlorophyll vs. chloroplast

Explanation

Chlorophyll makes plants green. It's basically a group of green pigments used by organisms that convert sunlight into energy via photosynthesis. First used in 1819, the noun chlorophyll derives from the Greek words khloros, meaning "pale green" and phyllon, meaning "a leaf." Plants use chlorophyll to trap energy from the sun. Without this energy, plants would be unable to initiate the process of photosynthesis, which converts water and carbon dioxide into starches that plants can use for food.

Example Sentences

Unlike most plants, Balanophora contains no chlorophyll and cannot perform photosynthesis.

From Science Daily • Dec. 20, 2025

Under too much light, though, chlorophyll can enter a dangerous "triplet" state, producing reactive oxygen molecules that can damage cells.

From Science Daily • Oct. 22, 2025

Gradually the lower light levels into autumn reduces the production of the green pigment - chlorophyll - and the underlying colours of yellow, red and orange come through.

From BBC • Sep. 18, 2025

Naturally occurring dietary pigments such as anthocyanins, betalains and chlorophyll offer many health benefits, but rarely leave a mark.

From Salon • Jan. 20, 2025

Thanks to chlorophyll, plants are able to transform sunlight, water, and minerals into carbohydrates.

From "The Omnivore's Dilemma" by Michael Pollan