pond scum


: any of various algae (especially spirogyra) or cyanobacteria
: a mass of tangled filaments of algae or cyanobacteria in stagnant waters

Example Sentences

Recent Examples on the Web Peer at the cell structure in an onion's skin, examine a human hair or look at the busy microbial world of pond scum. Citizen Science Salon, Discover Magazine, 19 Mar. 2020 Treehugger reports: The pond scum in question is microcystin-LR (MC-LR), which makes water unsafe for drinking, swimming and fishing in many parts of the world. Smriti Rao, Discover Magazine, 10 Mar. 2010 After a lovely day of rolling in the grass, digging in the dirt, playing in mud or pond scum, bathe your pet with Calm Shampoo, which is a one-of-a-kind day at the spa for Rocco & Roxie Supply Co.'s dogs. Amber Smith, Discover Magazine, 22 Oct. 2022 The plaque on your teeth is a biofilm; so too are infections on catheters, the slimy green of pond scum and the gunk clogging your bathtub drain. Carrie Arnold, Quanta Magazine, 2 Nov. 2022 In Earth's earliest fossil record, scientists study fossilized pond scum rather than bones or shells. Ashley Strickland, CNN, 3 Mar. 2021 And core samples from the watercourts contained a layer of dark gray sediment that appears to be on par with ancient pond scum. Alex Fox, Smithsonian Magazine, 2 Apr. 2020 The summer is hot, the water warm and people hoping to enjoy a pleasant day on Wisconsin’s lakes and rivers are instead turned away — disgusted at the soupy green blooms appropriately nicknamed pond scum. Lee Bergquist, Milwaukee Journal Sentinel, 19 Aug. 2019 Algix, a Mississippi company, is now making plastics from algae — from pond scum, to be precise. Ruth Kassinger, BostonGlobe.com, 26 July 2019 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'pond scum.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History

First Known Use

1864, in the meaning defined at sense 1

Time Traveler
The first known use of pond scum was in 1864

Dictionary Entries Near pond scum

Cite this Entry

“Pond scum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/pond%20scum. Accessed 2 Feb. 2023.

Kids Definition

pond scum

: spirogyra
also : any of various related algae
: a mass of tangled threads of algae in still water

More from Merriam-Webster on pond scum

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