A vocabulary of landscape — a landscape of words
1044 entries
dead reckoning
Navigating by tracking your course, speed, and time from a known starting point, without reference to landmarks or celestial observations. You calculate where you must be based on where you were and what you’ve done since. The method accumulates error with every mile. The name may derive from “deduced reckoning,” or it may just mean what it says — reckoning that gets you dead if you’re wrong.
Etymology
Dead here in the sense of absolute, exact, or direct — as in “dead ahead” and “dead center” — applied to reckoning (from Old English gerecenian, “to explain, account”), the working-out of position by calculation. The often-repeated claim that it comes from “deduced reckoning” (abbreviated “ded.”) is a later folk etymology; the “dead” spelling is attested earlier.