photosynthesis

1 of 2

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

photosynthetic

2 of 2

adjective

pho·​to·​synthetic ¦fōtō+ 

: using, relating to, or formed by photosynthesis

the direct or indirect source of free energy for all living organisms is the sunlight utilized by photosynthetic organisms

—S. L. Miller & H. C. Urey

photosynthetically

"+ 

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

Noun

This fungus can severely affect plants by blocking sunlight and hindering photosynthesis. —Sj McShane, Martha Stewart, 31 May 2026

Adequate Sunlight Above the soil surface, plants need ready access to sunlight to drive photosynthesis. —Kim Toscano, Southern Living, 29 May 2026

Nature’s Ammonia Factory Alongside photosynthesis, nitrogen fixation is one of the most essential chemical processes for life on Earth. —Quanta Magazine, 29 May 2026

Researchers linked hydrogenase enzymes directly to Photosystem I, a central component of photosynthesis. —Aamir Khollam, Interesting Engineering, 27 May 2026

Word History

Etymology

Noun

New Latin

First Known Use

Noun

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