retrocalculationn.
/ˌrɛtrəʊkalkjᵿˈleɪʃn/, U.S. /ˌrɛtroʊˌkælkjəˈleɪʃ(ə)n/ The action or process of calculating retrospectively; an instance of this.
ΚΠ
1664 H. Power Exper. Philos. Concl. 188 Which by retro-calculation will point out the time of the World's Nativity to be about 5000 years ago.
1820 C. Colton Lacon ccccxc. 204 A something similar attempt to correct the ancient chronology, has also been undertaken, by a retro-calculation of the eclipses.
1907 Observatory 30 310 On examining the dates with which ancient chronology presented us, it appeared that such of them as had not been verified by the modern retro-calculation of eclipses were very doubtful.
2005 Sci. Amer. (U.K. ed.) July 49/1 Our retrocalculations estimated that T. rex took 15 to 18 years to attain full size.
This entry has been updated (OED Third Edition, March 2010; most recently modified version published online March 2022).
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n.1664