epoch
UK[ˈiːpɒk]US[ˈepək]
n
A particular period of time in history or a person's life, typically one marked by notable events or particular characteristics.
n
The beginning of a distinctive period in the history of someone or something.
n
(Geology) A division of time that is a subdivision of a period and is itself subdivided into ages, corresponding to a series in chronostratigraphy.
n
(Astronomy) An arbitrarily fixed date relative to which planetary or stellar measurements are expressed.
Etymology
The word 'epoch' entered English in the early 17th century via Medieval Latin 'epocha', from Greek 'epokhē', meaning 'a stoppage, fixed point of time'. The Greek term derives from the verb 'epekhein', meaning 'to pause, hold back', which is a combination of 'epi-' ('on, at') and 'ekhein' ('to hold'). This original sense of a fixed point from which time is reckoned evolved logically into its modern meaning. From denoting a specific reference point in astronomy, it broadened to signify the distinctive period of history that begins from such a point, capturing the idea of a pivotal moment that 'holds' or defines an era.
Analysis
The word 'epoch' is a simplex loanword from Greek via Latin. It cannot be meaningfully segmented into productive morphemes using its modern English spelling.
Examples
The invention of the printing press marked a new epoch in the communication of ideas.
The rock layers were deposited during the Pleistocene epoch.
The satellite's coordinates were calculated for the epoch of 2020.0.