megayear

English

Etymology

Etymology tree

Proto-Indo-European *méǵh₂s

Proto-Hellenic *mégas

Ancient Greek μέγᾰς (mégăs)der.

English mega-

Proto-Indo-European *(H)yeh₁-der.?

Proto-Indo-European *yóh₁r̥der.

Proto-Germanic *jērą

Proto-West Germanic *jār

Old English ġēar

Middle English yeer

English year

English megayear

From mega- + year.

Noun

megayear (plural megayears)

2. A million years: a thousand thousand years.

   Synonyms: Myr, My, Ma (symbols); mega-annum, millionennium

   Holonyms: petasecond < giga-annum, gigayear < exasecond < zettasecond < yottasecond < ronnasecond < quettasecond

   Meronyms: quectosecond < rontosecond < yoctosecond < zeptosecond < attosecond < femtosecond < picosecond < nanosecond < microsecond < millisecond < centisecond < decisecond < second < decasecond < minute < hectosecond < kilosecond < hour < day < week < megasecond < fortnight < month < year < gigasecond < century < kiloannum, kiloyear, millennium < terasecond

   • 1984, J. B. Cadwallader-Cohen, W. W. Zysiczk, R. B. Donnelly, “The chaostron: an important advance in learning machines”, in Communications of the ACM, 27(4), p.357:

     After three hours the machine had not printed its response to the first input pattern; evidently the rate of learning under these conditions is very low (we judge it to be on the order of 10^-6 concepts for megayear).

   • 1997, Ian Lerche, Geological Risk and Uncertainty in Oil Exploration, page 231:

     We know from isotopic measurements, stereochemistry, and gas chromatography/mass spectrometry, that the production of hydrocarbons in the Earth occurs on timescales ranging from fractions of a megayear to hundreds of megayears, in a temperature regime in the rough range of 0-200°C, and in an evolving environmental "smog" of sedimentary pores containing water laced with varying amounts of ions, molecules, and minerals.

   • 2001, Fred Howard, Taming the Vipers in the Slough, page 400:

     As to that time span, all clearly definite forms of life or species seem to take a megayear more or less to come about and be present for a while.

Related terms

• MYA, Mya, mya (“million years ago”)