/i fem"euhr is/ , n. , pl. ephemerides /ef'euh mer"i deez'/ .
1. a table showing the positions of a heavenly body on a number of dates in a regular sequence.
2. an astronomical almanac containing such tables.
3. Archaic. an almanac or calendar.
[ 1545-55; ephemeris day book, diary ephemerís diary, account book, deriv. of ephémeros; see EPHEMERAL ]