ephemeris
UK[ɪˈfɛmərɪs]US[ɪˈfɛmərɪs]
n
a table or data file giving the calculated positions of a celestial object at regular intervals throughout a period.
Morpheme Breakdown
ephemer
is
ephemer
lasting a day
is
noun suffix
Etymology
the word 'ephemeris' originates from the greek 'ephēmeros', meaning 'lasting a day', which itself is formed from 'epi' (upon) and 'hēmera' (day). this sense of transience was adopted into latin as 'ephemeris', referring to a diary or journal—a record of daily events. in astronomical terminology, this concept was logically extended to denote a table of the daily positions of celestial bodies, capturing their seemingly transient locations against the sky from an earthly perspective.
Analysis
Structure: ephemer (lasting a day) + is (noun suffix)
ephemer (from greek ephēmeros, meaning 'lasting a day'); is (a latin suffix used to form nouns, often from greek -is)
Examples
the spacecraft's trajectory was calculated using a precise lunar ephemeris.
astronomers rely on a published ephemeris to locate planets and asteroids.
the old nautical almanac contained an ephemeris for the sun and major stars.