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

Example Sentences

Measurements of chlorophyll showed normal levels for nearly all pigments, except for a 20% drop in chlorophyll a, a light-sensitive compound.

From Science Daily • Nov. 24, 2025

For example, swapping chlorophyll and pheophytin in D2 could overcome the electron block, because chlorophyll needs lower activation energy than pheophytin.

From Science Daily • Oct. 13, 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

It has mouth parts adapted for piercing and sucking, and a prodigious appetite for the chlorophyll that makes the world green.

From "Silent Spring" by Rachel Carson