also dropout, "one who 'drops out' of something" (a course of education, life, etc.), 1930, from the verbal phrase drop out "withdraw or disappear from place" (1550s); see drop (v.) + out (adv.). 

also deadweight, 1650s, "weight of an inert body," from dead (adj.) + weight (n.). Hence, "a heavy or oppressive burden" (1721).

lake of the River Jordan, mid-13c., from dead (adj.); its water is 26 percent salt (as opposed to 3 or 4 percent in most oceans) and supports practically no life. In the Bible it was the "Salt Sea" (Hebrew yam hammelah), also "Sea of the Plain" and "East Sea." In Arabic it is al-bahr al-mayyit "Dead Sea." The ancient Greeks knew it as he Thalassa asphaltites "the Asphaltite Sea." Latin Mare Mortum, Greek he nekra thalassa (both "The Dead Sea") referred to the sea at the northern boundaries of Europe, the Arctic Ocean.

"in the exact middle," 1874, the noun phrase (1836) in reference to lathes or other rotating machinery, meaning the point which does not revolve; see dead (adj.).

1550s, "a pull exerting the utmost effort (of a horse), from dead (adj.) + lift (n.). From 1560s in figurative sense of "a position in which one can do no more;" by 1882 as "an effort involving the whole strength."

"piece of solemn music played at funerals," c. 1600, from dead + march (n.1).

"closed end of a passage," 1851 in reference to drainpipes, 1874 in reference to railway lines; by 1886 of streets; from dead (adj.) + end (n.). Figurative use, "course of action that leads nowhere," is by 1914. As an adjective in the figurative sense by 1917; as a verb by 1921. Related: Dead-ended; dead-ending; deadender (by 1996).

"a little drop," c. 1600, from drop (n.) + diminutive suffix -let.