Wikipedia:

Algae

Summary:

a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds. They are photosynthetic, like plants, and "simple" because they lack ...  (36 of 5744 words, 13 images, pronunciation)

Link:

http://en.wikipedia.org/wiki/Algae  [cite]

Columbia:

algae

Summary:

a large and diverse group of primarily aquatic plantlike organisms. These organisms were previously classified as a primitive subkingdom of the plant ...  (22 of 127 words, 1 etymology, pronunciation)

Link:

http://www.infoplease.com/ce6/sci/A0803306.html  [cite]

Britannica:

algae | alga [singular]

Summary:

Members of a group of mostly aquatic, photosynthetic organisms that defy precise definition. They range in size from the microscopic flagellate ...  (21 of 97 words)

Link:

http://www.britannica.com/EBchecked/topic/14828/algae  [cite]

Wikipedia:

Algae (disambiguation)

Summary:

a type of Protist. Algae may also refer to: Algae fuel, a biofuel | Algae (programming language) | Algae eaters, species that feed on algae | Snow algae, cold-tolerant species of algae | Ice algae, algae that live in sea ice | AlgaeBase, a database ...  (40 of 90 words, 6 senses)

Link:

http://en.wikipedia.org/wiki/Algae (disambiguation)  [cite]

Encarta:

alga | algae [plural] | algas [plural] | algal [adjective] | algoid [adjective]

Summary:

a photosynthetic organism of a group that lives mainly in water and includes the seaweeds. Algae differ from plants in not having true leaves, roots, ...  (25 of 85 words, 1 etymology, pronunciation)

Link:

http://encarta.msn.com/dictionary 1861584627/definition.html  [cite]

Random House:

algae | alga [singular]

Summary:

any of numerous groups of chlorophyll-containing, mainly aquatic eukaryotic organisms ranging from microscopic single-celled forms to multicellular ...  (17 of 72 words, pronunciation)

Link:

http://dictionary.infoplease.com/algae  [cite]

Merriam-Webster:

alga | algae [plural] | algas [plural] | algal

Summary:

a plant or plantlike organism of any of several phyla, divisions, or classes of chiefly aquatic usually chlorophyll-containing nonvascular organisms ...  (20 of 64 words, 1 etymology, pronunciation)

Link:

http://www.merriam-webster.com/dictionary/alga  [cite]

Wiktionary:

alga | algae [plural] | algaes [plural] | seaweed [hyponym] | algas [Spanish, plural]

Summary:

[biology] Any of many aquatic photosynthetic organisms, whose size ranges from a single cell to giant kelps and whose form is very diverse; some are eukaryotic and some prokaryotic; includes the seaweeds.  (32 of 45 words, pronunciation)

Link:

http://en.wiktionary.org/wiki/alga  [cite]