Pl. ephemeræ, -as. [a. mod.L. ephēmera (? sc. musca): see prec.]
In med.L. ephemera was neut. pl., a. Gr. ἐφήμερα used in this sense by Aristotle (see EPHEMERON). The earlier Eng. instances are possibly due to the common practice of treating plurals in -a as sing. Linnæus however used the word as fem., making it the name of a genus (of much wider extent than the genus now so called.)]
1. An insect that (in its imago or winged form) lives only for a day. In mod. entomology the name of a genus of pseudo-neuropterous insects belonging to the group Ephemeridæ (Day-flies, May-flies).
1677. Hale, Prim. Orig. Man., II. vi. 170. But Ephemeraes in duration, and little other than Insects in extent.
1750. Johnson, Rambler, No. 82, ¶ 7. I … have discovered a new ephemera.
1813. Bingley, Anim. Biog. (ed. 4), III. 235. The Common Ephemera, or Day-fly.
1873. Dawson, Earth & Man, vi. 136. May-flies and shad-flies, or ephemeras, which spend their earlier days under water.
2. transf. and fig. One who or something that has a transitory existence.
1751. Johnson, Rambler, No. 145, ¶ 11. These papers of a day, the Ephemeræ of learning.
1785. Crabbe, Newspaper, Wks. 1834, II. 119. These base ephemeras, so born To die before the next revolving morn.
1815. W. H. Ireland, Scribbleomania, 58, note. When the new-fangled ephemeræ of fashion shall be no more.
1886. H. F. Lester, Under two Fig Trees, 33. [A charwoman is] a kind of domestic ephemera which flutters briefly in the scullery and then is seen no more.
