Meaning of RECKONING in English
( n. )
The calculation of a ship's position, either from astronomical observations, or from the record of the courses steered and distances sailed as shown by compass and log, -- in the latter case called dead reckoning (see under Dead); -- also used for dead reckoning in contradistinction to observation.
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012