pho·​to·​syn·​the·​sis | \ ˌfō-tō-ˈsin(t)-thə-səs How to pronounce photosynthesis (audio) \

Definition of photosynthesis

: synthesis of chemical compounds with the aid of radiant energy and especially light especially : formation of carbohydrates from carbon dioxide and a source of hydrogen (such as water) in the chlorophyll-containing cells (as of green plants) exposed to light

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Other Words from photosynthesis

photosynthesize \ ˌfō-​tō-​ˈsin(t)-​thə-​ˌsīz How to pronounce photosynthesize (audio) \ intransitive verb
photosynthetic \ ˌfō-​tō-​sin-​ˈthe-​tik How to pronounce photosynthetic (audio) \ adjective
photosynthetically \ ˌfō-​tō-​sin-​ˈthe-​ti-​k(ə-​)lē How to pronounce photosynthetically (audio) \ adverb

Photosynthesis Has Greek Roots

The Greek roots of photosynthesis combine to produce the basic meaning "to put together with the help of light". Photosynthesis is what first produced oxygen in the atmosphere billions of years ago, and it's still what keeps it there. Sunlight splits the water molecules (made of hydrogen and oxygen) held in a plant's leaves and releases the oxygen in them into the air. The leftover hydrogen combines with carbon dioxide to produce carbohydrates, which the plant uses as food—as do any animals or humans who might eat the plant.

Examples of photosynthesis in a Sentence

Recent Examples on the Web Because dust clouded the atmosphere and blocked the sun, photosynthesis slowed and phytoplankton in oceans stopped producing oxygen. Scottie Andrew, CNN, "The asteroid that wiped out most life on Earth was a hotbed for bacteria. They were the first organisms to bounce back," 4 Feb. 2020 Bubbles of oxygen accumulated as photosynthesis pumped away. David W. Brown, New York Times, "This Robot’s Journey to an Icy Alien Moon Starts Beneath Antarctica," 3 Jan. 2020 At first glance a real tree seems a better bet: photosynthesis drives plant growth, capturing carbon dioxide. François Lévêque, Quartz, "The international sustainability, economics, and history of Christmas trees, explained," 21 Dec. 2019 The solar energy that photosynthesis stored away in the plants’ leaves and wood gets turned into electricity when that biomass is burned. The Economist, "Climate policy needs negative carbon-dioxide emissions," 5 Dec. 2019 Energy-producing mitochondria power all complex cells; chloroplasts, where photosynthesis takes place, make plant life possible. Elizabeth Pennisi, Science | AAAS, "A love of insects and their microbial partners helped this biologist reveal secrets of symbiosis," 14 Nov. 2019 The reason for this difference is that plants that grow in these environments do photosynthesis slightly differently, leading to distinctive ratios of carbon-13 and carbon-12. Stephanie De Marco, Los Angeles Times, "Bones pulled from the La Brea Tar Pits show the perils of being a picky eater," 26 Aug. 2019 Through photosynthesis, the plants and trees of the Amazon absorb billions of tons of carbon dioxide from the air each year, which helps limit how much of the heat-trapping gas is in the atmosphere. Drew Kann, CNN, "The Amazon is a key buffer against climate change. A new study warns wildfires could decimate it," 10 Jan. 2020 Powered by photosynthesis, these microorganisms absorb sunlight, nutrients, and carbon dioxide and spit out calcium carbonate—the rigid compound found in seashells and cement. Sophie Bushwick, Scientific American, "Bacteria-Filled Bricks Build Themselves," 15 Jan. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'photosynthesis.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of photosynthesis

1898, in the meaning defined above

History and Etymology for photosynthesis

New Latin

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Time Traveler for photosynthesis

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The first known use of photosynthesis was in 1898

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Last Updated

17 Feb 2020

Cite this Entry

“Photosynthesis.” Dictionary, Merriam-Webster, Accessed 29 Feb. 2020.

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How to pronounce photosynthesis (audio)

English Language Learners Definition of photosynthesis

biology : the process by which a green plant turns water and carbon dioxide into food when the plant is exposed to light


pho·​to·​syn·​the·​sis | \ ˌfō-tə-ˈsin-thə-səs How to pronounce photosynthesis (audio) \

Kids Definition of photosynthesis

: the process by which green plants and a few other organisms (as some protists) form carbohydrates from carbon dioxide and water in the presence of light

Other Words from photosynthesis

photosynthetic \ -​sin-​ˈthe-​tik \ adjective photosynthetic activity


pho·​to·​syn·​the·​sis | \ ˌfōt-ō-ˈsin(t)-thə-səs How to pronounce photosynthesis (audio) \
plural photosyntheses

Medical Definition of photosynthesis

: synthesis of chemical compounds with the aid of light sometimes including the near infrared or near ultraviolet especially : the formation of carbohydrates from carbon dioxide and a source of hydrogen (as water) in chlorophyll-containing cells (as of green plants) exposed to light involving a photochemical release of oxygen through the decomposition of water followed by various enzymatic synthetic reactions that usually do not require the presence of light

Other Words from photosynthesis

photosynthesize \ -​ˌsīz How to pronounce photosynthesize (audio) \ also British photosynthesise intransitive verb photosynthesized also British photosynthesised; photosynthesizing also British photosynthesising
photosynthetic \ -​sin-​ˈthet-​ik How to pronounce photosynthetic (audio) \ adjective
photosynthetically \ -​i-​k(ə-​)lē How to pronounce photosynthetically (audio) \ adverb

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Spanish Central: Translation of photosynthesis

Nglish: Translation of photosynthesis for Spanish Speakers Encyclopedia article about photosynthesis

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