1Lasting or existing for a long or apparently infinite time; enduring or continually recurring.

他对媒体的长期不信任。

一再出现的都市危机。

1. 1.1 (of a plant) living for several years.
   （植物）多年生的
   tarragon is perennial

   Compare with annual, biennial

   Example sentencesExamples

   • Weeds wither within a few minutes (though perennial weeds will require repeat applications).
   • Fertilizers formulated for perennial flowers are usually fine.
   • The perennial herb is native to southern Europe, Asia and the Mediterranean.
   • As perennial plants grow, they can fill the entire pot with their roots.
   • It may be tempting to choose perennial species for your garden by looks alone.
   • There are some hardy perennial plants that we, as gardeners, simply must have.
   • In general, avoid sowing seed of any annual grasses into a lawn of perennial grasses.
   • Therefore, cattle could not be moved directly from wheat pasture to cool season perennial grass.
   • However, most studies of plant defense genes have been performed on annual or short-lived perennial weeds or crop species.
   • But in a perennial flower bed, you might want something more permanent and decorative.
   • Paraquat may severely injure some perennial grasses, such as Kentucky bluegrass.
   • Grasses other than perennial ryegrass give a poor return for money spent on fertiliser.
   • The bulbs can remain in the same location year after year and thus act as perennial plants.
   • They are also used quite effectively when planted in close groups among perennial shrubs.
   • Dormancy also occurs in summer in some perennial grasses originating from Mediterranean climates.
   • If the weeds are sparse, use that early spring energy to hand pull some of those perennial weeds.
   • Perennial ryegrass is excellent for use in creep grazing pastures for young animals.
   • Perennial weeds growing from underground structures are capable of growing through organic mulches.
   • If you plant perennial herbs in the vegetable garden, set them off so they'll be easy to avoid during spring and fall tilling.
   • Eliminate weeds, especially perennial weeds, before planting to reduce weed problems later.
2. 1.2attributive (of a person) apparently permanently engaged in a specified role or way of life.
   （人）定型的，不变的
   he's a perennial student

   他永远是一个学生。

   Example sentencesExamples

   • Perhaps you are a collector of qualifications - a perennial student.
   • Few scholars of our time have so exemplified the permanent student and perennial teacher.
   • Destined, it seems, to be cast in the role of perennial dark horses, too often they have taken a tumble at an early fence.
   • Their coach was cautious about his team's chances of finally ending its role as perennial second to Munich.
   • As a perennial student of crime, I am here to tell you that there is no such thing as a monster.
   • He puts up big numbers, fits perfectly within a team concept, and plays a central role on a perennial powerhouse.
   • Despite a massive budget and state-of-the-art facilities including not one but two test tracks, they remain perennial underachievers.
   • Scotland's coach does not usually want for words, but even the perennial optimist found it difficult to see any highlights amongst the autumnal gloom of yesterday's encounter.
   • And yes, even the players acknowledge the team is a perennial underachiever.
3. 1.3 (of a stream or spring) flowing throughout the year.
   （溪流，泉水）常年的，终年的
   Example sentencesExamples

   • Can you think of some measures to control the flow of these natural and perennial springs?
   • Greenery crouches around the few perennial streams and artificially filled waterholes.
   • The cities and towns of the Kingdom are located on or near side wadis that used to have perennial flow emerging from springs.
   • He said priorities include the implementation of the decision taken on agriculture, to have drop-down irrigation schemes along perennial rivers.
   • This is unlike the situation in perennial lakes where sedimentation also occurs on sloping margins, thus perpetuating variations in depth.
   • Local people say the pond is slowly dying as the perennial spring which fed the waters has been choked by a slab laid for the construction of a building.
   • The ‘curse’ of Namibia is that the country's perennial rivers are far from the interior.
   • I can show how to make a perennial river in a six-minute film.
   • Water availability is a major challenge as the Lusitu river which used to be a perennial river has virtually dried up largely due to damming activities in Mazabuka up stream.
   • The once stable, slow - moving, marshy perennial river transformed into an unstable, flood-prone, intermittent stream.
   • The Okavango River is quite unique in that it is the only perennial river in Africa that flows eastwards without reaching the ocean.
   • With essential resources at a nadir, the Valparai plateau with its perennial streams obviously attracts elephant herds.
   • Among Anza-Borrego's wetlands is Coyote Creek, a perennial stream in the northwest corner of the park.
   • The greatest concentrations of game in Namibia can be found in Etosha National Park, an enormous silvery depression ringed by perennial springs.
   • Up to 99 percent of the water in the perennial rivers of the Chihuahuan Desert is diverted to municipal water supplies or to irrigate fields.
   • The sequence may be random, erratic or a continuous pattern (for some time) but like a perennial river, the thought flow goes on.
   • Northern Province is undoubtedly one of the most blessed parts of Zambia with abundant perennial streams that run throughout the year.
   • There are nearly 10,000 ponds and nearly 2,000 perennial streams.
   • After we turned the river Arvari into a perennial river through water harvesting, the government started to give out licenses for fishing in that river.
   • It has been found that the density of perennial streams relates directly to the available moisture, which is defined as precipitation minus evapotranspiration.

A perennial plant.