noun

alga

AL-guh

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Alga (noun) means a simple aquatic organism that makes its own food by photosynthesis, ranging from a single cell to huge seaweeds such as giant kelp. Example: “The pond had turned green because an alga was multiplying in the warm water.”

noun

A simple aquatic organism that makes its own food by photosynthesis, ranging from a single cell to huge seaweeds such as giant kelp.

"The pond had turned green because an alga was multiplying in the warm water."

"Kelp is a large alga that grows in dense forests off some coasts."

"Under the microscope, each alga looked like a tiny green bead."

How to use alga

Learner’s notes

In plain EnglishAn alga is a simple water-living organism that makes food from sunlight, from a tiny single cell up to big seaweeds.

When to use it

It is a biology term, mostly found in science writing and teaching.

Memory tip

Alga is the singular and algae is the plural, so say one alga but two algae.

Trace the full origin ↓

Easily confused with

algae → algal fungus → moss →

Common pairings

green alga red alga brown alga golden alga

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C2 · Advanced serendipity Fortunate discoveries made entirely by accident.

Gen Z slang rizz Charm — the ability to attract a romantic interest.

B2 · Intermediate empathy The capacity to share another person’s feelings.

C1 · Advanced nonchalant Casually calm and relaxed; unconcerned.

Internet slang delulu Delusional — believing something against the odds.

Etymology nostalgia Greek nostos “return home” + algos “pain”.

C2 · Advanced serendipity Fortunate discoveries made entirely by accident.

Gen Z slang rizz Charm — the ability to attract a romantic interest.

B2 · Intermediate empathy The capacity to share another person’s feelings.

C1 · Advanced nonchalant Casually calm and relaxed; unconcerned.

Internet slang delulu Delusional — believing something against the odds.

Etymology nostalgia Greek nostos “return home” + algos “pain”.

Test yourself on “alga” A quick quiz — meaning, synonyms & usage →

Fill the gap

Can you complete this real example?

The pond had turned green because an _____ was multiplying in the warm water.

Etymology

The word comes straight from Latin, where it was also spelt alga.

Origin: Latin

Synonyms

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algae

Related words

algae

Frequently asked questions

What is the plural of alga?

The usual plural is algae. An older spelling, algæ, is now archaic.

Is algaes a word?

Algaes is not a standard plural. Use algae when you mean more than one alga.

Is seaweed an alga?

Yes, seaweeds are included among the algae. The group also covers much smaller forms, down to single cells.

What is the meaning of alga?

"alga" (noun) means a simple aquatic organism that makes its own food by photosynthesis, ranging from a single cell to huge seaweeds such as giant kelp.

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