pho·to·syn·the·sis | \ˌfō-tō-ˈsin(t)-thə-səs \

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 \ intransitive verb
photosynthetic \ˌfō-tō-sin-ˈthe-tik \ adjective
photosynthetically \ˌfō-tō-sin-ˈthe-ti-k(ə-)lē \ 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

Some use chlorophyll to convert sunlight during photosynthesis and others use rhodopsins, proteins that bind to a form of vitamin A called retina to capture light. Shandria Sutton, Science | AAAS, "New ‘light-eating’ protein discovered in the Sea of Galilee," 5 July 2018 In Chlamydomonas, an ancient stress response pathway blocks reproduction at night, when photosynthesis shuts down and resources are scarcer. Elizabeth Pennisi, Science | AAAS, "The momentous transition to multicellular life may not have been so hard after all," 28 June 2018 That photosynthesis is one of the ways the ocean eliminates carbon dioxide on the planet. David Grossman, Popular Mechanics, "NASA Is Stepping Into the Twilight Zone," 19 June 2018 Many bacteria are already capable of turning sunlight into energy using photosynthesis. Avery Thompson, Popular Mechanics, "Clouds Are No Problem for New Bacteria-Powered Solar Panels," 6 July 2018 What about technologies like, say, artificial photosynthesis? New York Times, "SoftBank Wants to Build the Future. Here Are Some New Bets It Could Make.," 14 June 2018 That’s in contrast to most other plants, which derive energy from the sun using photosynthesis. Sean Greene,, "A rare great ape, a 130-foot-tall tree and an extinct marsupial lion make the Top 10 New Species list for 2018," 23 May 2018 But exceptionally high temperatures are known to greatly reduce photosynthesis—and most existing plant models suggest this should also decrease transpiration, leaving trees in danger of fatally overheating. Yasemin Saplakoglu, Scientific American, "Trees Sweat to Keep Cool," 12 Apr. 2018 Meanwhile, the moss inhales carbon dioxide and releases oxygen via photosynthesis—in effect cleaning the air. Bengt Halvorson, Car and Driver, "Goodyear’s New Concept Tire Has Living Moss Inside—Really," 7 Mar. 2018

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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Last Updated

13 Oct 2018

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Time Traveler for photosynthesis

The first known use of photosynthesis was in 1898

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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 \

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 \
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 \ also British photosynthesise intransitive verb photosynthesized also British photosynthesised; photosynthesizing also British photosynthesising
photosynthetic \-sin-ˈthet-ik \ adjective
photosynthetically \-i-k(ə-)lē \ adverb

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More from Merriam-Webster on photosynthesis

Spanish Central: Translation of photosynthesis

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

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