perennial

1. not comparableLasting or remaining active throughout the year, for multiple years, or all the time.

   a perennial stream

   5 more examples

   [W]hat is most admirable is the vast enclosure, and variety of ground, in yᵉ large garden, containing vineyards, cornefields, meadows, groves (whereof one is of perennial greens), and walkes of vast lengthes, so accurately kept and cultivated, that nothing can be more agreeable.

   1644 March 7 (Gregorian calendar), John Evelyn, “[Diary entry for 27 February 1644]”, in William Bray, editor, Memoirs, Illustrative of the Life and Writings of John Evelyn, […], 2nd edition, volume I, London: Henry Colburn, […]; and sold by John and Arthur Arch, […], published 1819, →OCLC, page 43

   And there is ſuch a thing as Subterraneous Heat, […] [a]s is manifeſt from the ſmoking of perennial Fountains in froſty VVeather, and VVater dravvn out of Pumps and open VVells.

   1713, W[illiam] Derham, “[A Survey of the Terraqueous Globe.] The Distribution of the Earth and Waters.”, in Physico-Theology: Or, A Demonstration of the Being and Attributes of God, from His Works of Creation. […], London: […] W[illiam] Innys, […], →OCLC, book II (Of the Terraqueous Globe It Self, in General), footnote 3, pages 49–50

   It [the pond] is a clear and deep green well, half a mile long and a mile and three quarters in circumference, and contains about sixty-one and a half acres; a perennial spring in the midst of pine and oak woods, without any visible inlet or outlet except by the clouds and evaporation.

   1854 August 9, Henry D[avid] Thoreau, “The Ponds”, in Walden; or, Life in the Woods, Boston, Mass.: Ticknor and Fields, →OCLC, page 191

   That desert's age the gorge may prove, / Piercing profound the mountain bare; / Yet hardly churned out in the groove / By a perennial wear and tear / Of floods; nay, dry it shows within; / But twice a year the waters flow, / Nor then in tide, but dribbling thin: […]

   1876, Herman Melville, “Canto I. In the Mountain.”, in Clarel: A Poem and Pilgrimage in the Holy Land. […], volume II, New York, N.Y.: G[eorge] P[almer] Putnam’s Sons […], →OCLC, part III (Mar Saba), page 306

   These offshore Sonoman mountains likely formed an orogenic (mountainous) barrier to moisture inland, resulting in a mountain-shadow onshore desert punctuated by regional annual and large basin perennial streams draining into a forearc saline sea.

   2012, Chinle Miller, “The Tectonic Forces of the Mesozoic”, in In Mesozoic Lands: The Mesozoic Geology of Arches and Canyonlands National Parks, Kindle edition, page 34

   Synonyms: multiyear, yearslong, perennal

2. figurativelynot comparableContinuing without cessation or intermission for several years, or for an undetermined or infinite period; never-ending or never failing; perpetual, unceasing.

   His artwork has a perennial beauty.

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   There, on perennial Adamant deſign'd, / The various Fortunes of your Race you'll find: […]

   1717, Leonard Welsted, “Book XV. [The Deification of Julius Cæsar.]”, in Ovid’s Metamorphoses in Fifteen Books. […], London: […] Jacob Tonson, […], →OCLC, page 545

   Good humour may be defined a habit of being pleaſed, a conſtant and perennial ſoftneſs of manner, eaſineſs of approach, and ſuavity of diſpoſition; […]

   1750 December 4 (Gregorian calendar), Samuel Johnson, “No. 72. Friday, November 24. 1750.”, in The Rambler, volume III, Edinburgh: [[…] Sands, Murray, and Cochran]; sold by W. Gordon, C. Wright, J. Yair, […], published 1750, →OCLC, page 155

   The perennial exiſtence of bodies corporate and their fortunes, are things particularly ſuited to a man who has long views; who meditates deſigns that require time in faſhioning; and which propoſe duration when they are accompliſhed.

   1790 November, Edmund Burke, Reflections on the Revolution in France, and on the Proceedings in Certain Societies in London Relative to that Event. […], London: […] J[ames] Dodsley, […], →OCLC, page 232

   Has Ireland been governed in a 'wise and loving' manner? A government and guidance of white European men which has issued in perennial hunger of potatoes to the third man extant,—ought to drop a veil over its fact, and walk out of court under conduct of proper officers; saying no word; expecting now of a surety sentence either to change or die.

   1839 (indicated as 1840), Thomas Carlyle, “Finest Peasantry in the World”, in Chartism, London: James Fraser, […], →OCLC, page 25

   She has a large gold eye-glass, has Lady Tippins, to survey the proceedings with. If she had one in each eye, it might keep that other drooping lid up, and look more uniform. But perennial youth is in her artificial flowers, and her list of lovers is full.

   1864 May – 1865 November, Charles Dickens, “A Marriage Contract”, in Our Mutual Friend. […], volume I, London: Chapman and Hall, […], published 1865, →OCLC, 1st book (The Cup and the Lip), page 90

   Synonyms: continual, enduring, everlasting, permanent, timeless, ageful, agelong, amaranthine

3. figurativelynot comparableAppearing or recurring again and again; recurrent.

   a perennial candidate in elections

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   Change is a perennial theme in politics.

   Ludgate Hill is not Moirosi’s Mountain, but, after all, is only a gentle ascent of about half an inch in the foot, over a length of about two hundred yards, up which unshod omnibus horses would trot with a full load in any weather. Yet there it must remain, a chief thoroughfare in the heart of London, a perennial cause of complaint, and of fear, disgust, and injury to man and horse.

   1881, “Free-lance” [pseudonym; J. T. Denny], “Ludgate Hill only Rises about Four Feet in Every Hundred—Societies—the Bearing Rein only Required on Cripples”, in Horses and Roads: Or How to Keep a Horse Sound on His Legs […], 3rd edition, London: Longmans, Green, and Co., →OCLC, page 129

   Of all the questions which, throughout the centuries, have escaped from the lips of man, there is none which has been asked with such persistence, none which has possessed interest more perennial, than "Whence do I come? Whither shall I go?" Man's origin, man's hereafter, have ever been of intensest interest to man.

   1886, Annie Besant, Life, Death, and Immortality, London: Freethought Publishing Company, […], →OCLC, page 3

   Synonyms: repetitious, habitual, monotonous, recurrent, recurring, repeating, repetitional, repetitionary

   1. figurativelynot comparablerareAppearing again each year; annual.

      Synonyms: repetitious, habitual, monotonous, recurrent, recurring, repeating, repetitional, repetitionary

4. not comparablebiologyOf a plant: active throughout the year, or having a life cycle of more than two growing seasons.

plural perennials

1. biologyA plant that is active throughout the year, or has a life cycle of more than two growing seasons.

   1 more example

   One would have supposed from the appearance of the country at the end of the first season after the eruption that practically all plants except the trees and bushes had been destroyed, and that revegetation must be due to new seedlings started on the ash. Such, however, is not the case. Excavation of the root systems of the new plants shows that they are old perennials which have come through the ash from the old soil.

   1917 January, Robert F[iske] Griggs, “The Valley of Ten Thousand Smokes”, in National Geographic, volume XXXI, number 1, Washington, D.C.: National Geographic Society […], →ISSN, →OCLC

2. broadlyA thing that lasts forever.
3. broadlyA person or thing (such as a problem) that appears or returns regularly.

   Some of the stars on our list are perennials who fill huge venues year after year after year, but there's also a returning superstar on our list of the hottest summer tours of 2019.

   2019 June 21, Sterling Whitaker, “Hottest Country Tours to See in Summer 2019”, in Taste of Country, archived from the original on 31 May 2021