photosynthesis

noun

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

: 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

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

Did you know?

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

Once considered more similar to plants than animals, fungi can’t create their own food through photosynthesis; instead, most of them obtain nutrients from dead or decaying organic matter. —Lauren Oster, Smithsonian Magazine, 12 May 2025

Lamm had become interested in the way that various algae can capture carbon by absorbing it through photosynthesis before sinking to the bottom of the sea. —D. T. Max, New Yorker, 7 Apr. 2025

At a time when ocean acidification threatens the survival of the world’s coral reefs and the thousands of fish species that inhabit them, seagrasses reduce acidity by absorbing carbon through photosynthesis, according to a 2021 report by the University of California. —Ian Urbina, Los Angeles Times, 28 Mar. 2025

According to the research this unusual coloration was underpinned by the unique water chemistry of the time and the evolution of photosynthesis. —New Atlas, 27 Apr. 2025

Word History

Etymology

New Latin

First Known Use

1898, in the meaning defined above

Rhymes for photosynthesis

• biosynthesis
• nucleosynthesis
• synthesis
• synthesise

Kids Definition

photosynthesis

noun

pho·​to·​syn·​the·​sis ˌfōt-ə-ˈsin(t)-thə-səs 

: the process by which plants and some bacteria and protists that contain chlorophyll make carbohydrates from water and from carbon dioxide in the air in the presence of light

photosynthetic

-sin-ˈthet-ik 

adjective

Medical Definition

photosynthesis

noun

pho·​to·​syn·​the·​sis ˌfōt-ō-ˈsin(t)-thə-səs 

plural photosyntheses

: 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

photosynthesize

-ˌsīz 

intransitive verb

also British photosynthesise

photosynthesized also British photosynthesised; photosynthesizing also British photosynthesising

photosynthetic

-sin-ˈthet-ik 

adjective

photosynthetically

-i-k(ə-)lē 

adverb