"ascertaining of the position of a ship by measurement of the distance run" (without observation of heavenly bodies), 1610s, perhaps from nautical abbreviation ded. ("deduced") in log books, but it also fits dead (adj.) in the sense of "unrelieved, absolute."
de-accession
deacon
deactivate
dead
dead end
dead reckoning
Dead Sea
deadbeat
dead-center
deaden
Deadhead
