dead reckoning

American  

noun

Navigation.

1. calculation of one's position on the basis of distance run on various headings since the last precisely observed position, with as accurate allowance as possible being made for wind, currents, compass errors, etc.

2. one's position as so calculated.

---

dead reckoning British  

noun

1. a method of establishing one's position using the distance and direction travelled rather than astronomical observations

---

Etymology

Origin of dead reckoning

First recorded in 1605–15