"pertaining to the geological period between the Oligocene and Pliocene," 1831, irregular formation from Greek meion "less" (from PIE root *mei- (2) "small") + -cene "new, recent." The intention is "the middle division of the Tertiary period."
A typical example of the monstrosities with which scientific men in want of a label for something, and indifferent to all beyond their own province, defile the language. The elements of the word are Greek, but not the way they are put together, nor the meaning demanded of the compound. [Fowler]
in geology, in reference to the most recent division of the Tertiary, 1833, from plio- "more" (Latinized form of pleio-) + -cene "recent." Execrated by classical purists (along with Miocene and Eocene); a proper form from Greek would be *Plionocene. Roughly 5.3 million to 2.6 million years ago, it is distinguished from the other two epochs by having more fossils of still-existing species. The Pliocene and the more recent Pleistocene, both comparatively brief, commonly now are combined as the Plio-Pleistocene.
in reference to the second epoch of the Tertiary Period, 1831, from eo- "earliest" + Latinized form of Greek kainos "new" (see -cene). Coined in English (along with Miocene and Pliocene) by the Rev. William Whewell, English polymath, and meant as "the dawn of the recent." As a noun from 1851.
It has occurred to me that [kainos] is a better word than [neos], and I propose for your terms, 1 acene, 2 eocene, 3 miocene, 4 pliocene. ... For eocene you might say spaniocene, but I like your eo better. Is not this shortest and best? [Whewell, letter to Lyell, Jan. 31, 1831]
Proto-Indo-European root meaning "small."
It forms all or part of: administer; administration; comminute; diminish; meiosis; Menshevik; menu; metier; mince; minestrone; minim; minimum; minister; ministration; ministry; minor; minuend; minuet; minus; minuscule; minute; minutia; Miocene; mis- (2); mite (n.2) "little bit;" mystery (n.2) "handicraft, trade, art;" nimiety.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit miyate "diminishes, declines;" Greek meion "less, smaller;" Latin minus, minor "smaller," minuere "to diminish, reduce, lessen;" Old English minsian "to diminish;" Russian men'she "less."
1856, in geology, "pertaining to the Tertiary period between the Eocene and the Miocene," now defined roughly as 34 million to 23 million years before the present, coined in German (1854) by paleontologist Heinrich Ernst von Beyrich (1815-1896), from oligo- "small, little, few" + -cene. So called because few modern fossils were found in Oligocene rocks, which were especially prominent in northern Germany.
"the third great geological period," 1841, Cainozoic, from Latinized form of Greek kainos "new, fresh, recent, novel" (see recent) + zōon "animal," but here with a sense of "life" (from PIE root *gwei- "to live"). The era that began with the demise of the dinosaurs and the rise of "recent" species and continues to the present; it also is known as the Tertiary. Compare Paleozoic, Mesozoic.
We observe that Lyell, in his geological works, even the most recent, uses the word Cainozoic instead of Coenozoic or Cenozoic. Why the propounder of the terms Eocene, Miocene, etc., should thus spell the word is incomprehensible. If he is right in it, then to be consistent he ought to say Eocain, Miocain, Pliocain, Post-pliocain; for all have the same root καινός. [American Journal of Sciences and Arts, 1873]