🇺🇸
/ˈælɡə/
🇺🇸
/ˈælɡə/
🇬🇧
/ˈælɡə/
🇬🇧
/ˈælɡə/
Plural
algae
An alga is a simple, usually aquatic, photosynthetic organism — ranging from microscopic single-celled types (like Chlamydomonas) to large multicellular seaweeds (like kelp) — that lacks true roots, stems, leaves, and vascular tissue. Unlike plants, algae don’t produce flowers or seeds, and they’re essential oxygen producers and the base of many aquatic food chains; think of them as nature’s underwater solar panels.
Scientists discovered a new species of unicellular alga in Antarctic sea ice.
The lake turned green due to a harmful algal bloom caused by nutrient runoff.
Kelp forests are made up of large brown algae that provide habitat for countless marine species.
Many cosmetics contain extracts from red algae for their moisturizing properties.
Algae are increasingly used in biotechnology to produce biofuels and sustainable food proteins.
alga
Comes from Latin 'alga', meaning 'seaweed' or 'marine plant'. The Latin term itself likely derives from an unknown pre-Latin Mediterranean source, possibly related to Proto-Indo-European *h₂elǵ- ('to burn, shine, be bright')—reflecting the shimmering, iridescent appearance of some seaweeds in sunlight—or more plausibly from a substrate word adopted into Latin via Greek (ἀλγή, algḗ), where it meant 'seaweed' and carried connotations of marine vegetation, sliminess, or growth in brackish water. Examples include alga, algae, algal, phycology (from Greek 'phycos' = seaweed), and agar (a gelatinous substance extracted from red algae). Core meaning: 'simple photosynthetic aquatic organism, especially non-vascular and often microscopic or colonial'.