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

Through photosynthesis, grass and other plants pull carbon dioxide from the atmosphere and turn it into sugars. —Dr. Avishesh Neupane, Hartford Courant, 21 Mar. 2026

Missions to Mars have looked for signs of photosynthesis – the process by which plants take in energy – and telescopes peering deep into space look for oxygen, which organisms on Earth release into the atmosphere. —Mary Magnuson, The Conversation, 20 Mar. 2026

Another technique used at Barone Pizzini is spraying kaolin, a white dust, on the leaves to improve photosynthesis and reflect solar rays. —Mike Desimone, Robb Report, 8 Mar. 2026

These nutrients are gradually released in low concentrations over a long period of time and roses absorb them and use them to produce their own food in the form of sugars through the process of photosynthesis. —Rita Perwich, San Diego Union-Tribune, 7 Mar. 2026

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