Meaning & use
algae
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Meanings
nounpluralbiology
A group of simple plant-like living things, mostly found in water, that make food from sunlight but have no true roots, stems, or leaves.
Grammar: Plural of alga but often used with a singular verb: the algae is thick.
Patterns
- algae in something
- a bloom of algae
Green algae covered the surface of the pond.
Some algae are so small you need a microscope to see them.
Seaweed is a large kind of algae.
noununcountableinformal
The slimy green growth on walls, tanks, or pools caused by such organisms, seen as a nuisance.
Grammar: Often used as a mass noun for the green layer.
Patterns
- clean the algae off something
- algae on something
He scrubbed the algae off the aquarium glass.
Warm weather made algae grow on the pool walls.
Algae made the steps slippery after the rain.
Word forms
| singular | alga |
|---|
Common combinations
- algae bloom
- An algae bloom turned the lake bright green.
- green algae
- Green algae floated near the shore.
- blue-green algae
- Blue-green algae can be poisonous to dogs.
- grow algae
- Scientists grow algae for biofuel.
- marine algae
- Marine algae produce much of the world's oxygen.
Synonyms and how they differ
- seaweed
- Seaweed is a large, visible type of algae in the sea, so it is narrower than algae.
- pond scum
- Pond scum is a casual, unflattering term for floating algae on still water.
- phytoplankton
- Phytoplankton are tiny floating algae-like organisms in water, a more scientific and narrower word.
Word family
- alga noun
- singular form, one organism
- algal adjective
- relating to algae
- algicide noun
- a chemical that kills algae
- algology noun
- the scientific study of algae
Commonly confused: algae or fungi? algae or alga?
algae vs fungi
Fungi, like mushrooms and molds, do not make food from sunlight, while algae do.
algae vs alga
Alga is the correct singular, and algae the plural, though people often use algae for both.
Practice
Which sentence uses the singular form correctly?
Choose one answer.
Alga is the singular and algae is the plural. Algaes and algas are not standard forms.
Make it your own
Write a sentence using “algae”, then check it and compare it with the examples above.