English Reference

Word

algae

Phoneticsal·gae

US/ˈæɫdʒi/

UK/ˈælɡiː/

Definition

n. simple organisms that grow in water and use sunlight to make food, like seaweed or pond scum.

n. photosynthetic, eukaryotic organisms that lack true roots, stems, and leaves; the term is often used collectively for the green or brown mass found in water.

Examples

“Green algae grew on the old pond stones.”

“The clear lake water allowed sunlight to reach the bottom, helping the algae grow quickly.”

“Marine biologists study how rising ocean temperatures affect algae blooms, which can disrupt local ecosystems and oxygen levels.”

Examples

simple

“Green algae grew on the old pond stones.”

contextual

“The clear lake water allowed sunlight to reach the bottom, helping the algae grow quickly.”

complex

“Marine biologists study how rising ocean temperatures affect algae blooms, which can disrupt local ecosystems and oxygen levels.”

Pitfall

The algae is growing fast.

The algae are growing fast.

In scientific and formal writing, 'algae' is the plural of 'alga' and takes a plural verb.

Real-World Examples

“Changes in sea ice cover also affect algae, which form the base of the food web.”
Phys.org · 3 Sept 2026
“Near brightly lit cave entrances, several kinds of algae and plants grew in the water.”
ScienceDaily · 4 Aug 2026

Synonyms

This entry

Level
B2 · Upper Intermediate
Frequency
Frequent
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English Reference