ageratum

noun

ag·​er·​a·​tum ˌa-jə-ˈrā-təm How to pronounce ageratum (audio)
plural ageratum also ageratums
: any of a genus (Ageratum) of annual tropical American composite herbs often cultivated for their small showy heads of usually blue or white flowers
also : a related blue-flowered perennial (Conoclinium coelestinum)

Examples of ageratum in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Some that spring up for me include ageratums, verbena, ammi, nigella, and wheat celosia. —Dawn Pettinelli, Hartford Courant, 4 May 2024 Flowers to start from seed now include cannabis (autoflowers are best for Alaska), cosmos, snaps, ageratum, seed dahlias, godetia, aster, celosia, malva, salvia, lupine, brachyscome, dianthus, stock (seeds need light) and lockspar. —Jeff Lowenfels, Anchorage Daily News, 24 Mar. 2022 The 100-acre farm boasts 6 acres of annuals and perennials, from popular standbys (dahlias, zinnias and sunflowers) to dozens of others like dianthus, hellebores, ageratum and dill. —Mike Klingaman, baltimoresun.com, 16 Aug. 2021 Hardy ageratum is a native perennial that can be overly aggressive and grow up to three feet in height. —Janet Carson, Arkansas Online, 21 Sep. 2020

Word History

Etymology

borrowed from New Latin (Linnaeus), going back to Latin ageraton (Pliny), a plant, perhaps Achillea ageratum, borrowed from Greek agḗraton (Dioscorides), from neuter of agḗratos "ageless, undecaying," from a- a- entry 2 + -gēratos, derivative from the base of gêras "old age" — more at geronto-

Note: Introduced by Linnaeus in Hortus Cliffortianus (Amsterdam, 1737), p. 396. The name may have been suggested to Linnaeus by the resemblance of his Ageratum conyzoides to some species of Eupatorium, which, in pre-Linnaean nomenclature, were also called Ageratum; specifically, the plant now known as Achillea ageratum, which may have been the ancients' ageraton, was called by herbalists both Ageratum and Eupatorium mesues (e.g., in Joseph Miller's Botanicum officinale, or a Compendious Herbal, London, 1722, p. 18). In Genera Plantarum, 2. ed. (p. 392), Linnaeus notes that he departs from previous application of the name ("Aliud est Ageratum Boerhaavii, quod partim ad Achillæas, partim ad Tanaceta spectat"). In Dioscorides' account of the plant in Greek, agḗraton is so called because the flowers keep their form for a long time.

First Known Use

circa 1737, in the meaning defined above

Time Traveler
The first known use of ageratum was circa 1737

Rhymes for ageratum

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ager
ageratum
ageratum blue
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Cite this Entry

“Ageratum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/ageratum. Accessed 4 Nov. 2025.

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Kids Definition

ageratum

noun
ag·​er·​a·​tum ˌaj-ə-ˈrāt-əm How to pronounce ageratum (audio)
: any of a large genus of tropical American herbs related to the daisies and often cultivated for their small showy heads of blue or white flowers

More from Merriam-Webster on ageratum

Britannica.com: Encyclopedia article about ageratum

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