from The American Heritage® Dictionary of the English Language, 5th Edition.

  • adjective Lasting for a markedly brief time.
  • adjective Having a short lifespan or a short annual period of aboveground growth. Used especially of plants.
  • noun Something, especially a plant, that is ephemeral.

from The Century Dictionary.

  • In zoology, lasting but one day; ephemeric; ephemerous.
  • Hence Existing or continuing for a very short time only; short-lived; transitory.
  • Also, rarely, ephemeric.
  • Synonyms Transient, fleeting, evanescent.
  • noun Anything which lasts or lives but for a day or for a very short time, as certain insects.

from the GNU version of the Collaborative International Dictionary of English.

  • noun Anything lasting but a day, or a brief time; an ephemeral plant, insect, etc.
  • adjective Beginning and ending in a day; existing only, or no longer than, a day; diurnal.
  • adjective Short-lived; existing or continuing for a short time only.
  • adjective (Zoöl.) one of a group of neuropterous insects, belonging to the genus Ephemera and many allied genera, which live in the adult or winged state only for a short time. The larvæ are aquatic; -- called also day fly and May fly.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun Something which lasts for a short period of time.
  • adjective Lasting for a short period of time.
  • adjective biology Existing for only one day, as with some flowers, insects, and diseases.
  • adjective geology, of a body of water Usually dry, but filling with water for brief periods during and after precipitation.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun anything short-lived, as an insect that lives only for a day in its winged form
  • adjective lasting a very short time


from The American Heritage® Dictionary of the English Language, 4th Edition

[From Greek ephēmeros : ep-, epi-, epi- + hēmerā, day.]

from Wiktionary, Creative Commons Attribution/Share-Alike License

From New Latin ephemerus, from Ancient Greek ἐφήμερος (ephēmeros), the more common form of ἐφημέριος (ephemerios, "of, for, or during the day, living or lasting but for a day, short-lived, temporary"), from ἐπί (epi, "on") + ἡμέρα (hēmera, "day").


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  • The Mayfly is of the order ephemeroptera, which is a beautifully poetic way of describing the insect.

    July 7, 2007

  • You'd probably want to be born with a bit of poetry in your life if you only lived for a day.

    November 23, 2007

  • The Greek hêmera (day-break, daybreak, daylight, days, daytime), after the goddess Hemera of 'days', is the base for this beauty of a word. The hemero root was used to mean 'day', which gives the word its metaphorical relationship to all that is temporal or passing, as the passing of a day.

    November 26, 2007

  • "I felt it in the little square that lay in front of the theatre, in which, in two-hours' time, the bare boughs of the chestnut-trees would gleam with a metallic lustre as the lighted gas-lamps showed up every detail of their structure; and before the ticket attendants, whose selection, advancement and ultimate fate depended upon the great artist—for she alone held power in this administration at the head of which ephemeral and purely nominal managers followed one after the other in an obscure succession—who took our tickets without even glancing at us, so preoccupied were they in seeing that all Mme Berma's instructions had been duly transmitted to the new members of the staff, that it was clearly understood that the hired applause must never sound for her, that the windows must all be kept open so long as she was not on stage and every door closed tight the moment she appeared, that a bowl of hot water must be concealed somewhere close to her to make the dust settle."

    -- Within a Budding Grove by Marcel Proust, translated by C.K. Scott Moncrieff and Terence Kilmartin, Revised by D.J. Enright, p 22 of the Modern Library paperback edition

    March 5, 2008

  • "Her lists were made up and closed, so that while she wandered slowly through the Princess's rooms dropping into one ear after another: 'You won't forget tomorrow,' she had the ephemeral glory of averting her eyes, while continuing to smile, if she caught sight of some ugly duckling who was to be avoided or some country squire for whom the bond of a schoolboy friendship had secured admission to 'Gilbert's,' and whose presence at her garden-party would be no gain."

    --Sodom and Gomorrah by Marcel Proust, translated by C.K. Scott Moncrieff and Terence Kilmartin, revised by D.J. Enright, p 96 of the Modern Library paperback edition

    February 2, 2009

  • lasting a very short time

    The lifespan of a mayfly is ephemeral, lasting from a few hours to a couple of days.

    October 19, 2016