lurch (n.1)

"sudden pitch to one side," 1784, from earlier lee-larches (1765), a nautical term for "the sudden roll which a ship makes to lee-ward in a high sea, when a large wave strikes her, and bears her weather-side violently up, which depresses the other in proportion" ["Complete Dictionary of Arts and Sciences," London 1765]. This is perhaps from French lacher "to let go," from Latin laxus (see lax).

When a Ship is brought by the Lee, it is commonly occaſsioned by a large Sea, and by the Neglect of the Helm's-man. When the Wind is two or three Points on the Quarter, the Ship taking a Lurch, brings the Wind on the other Side, and lays the Sails all dead to the Maſt; as the Yards are braced up, ſhe then having no Way, and the Helm being of no Service, I would therefore brace about the Head ſails ſharp the other Way .... [John Hamilton Moore, Practical Navigator, 8th ed., 1784]

lurch (n.2)

"predicament," 1580s, from Middle English lurch (v.) "to beat in a game of skill (often by a great many points)," mid-14c. (implied in lurching), probably literally "to make a complete victory in lorche," an old game akin to backgammon, with a name of uncertain origin. Perhaps it is related to Middle English lurken, lorken "to lie hidden, lie in ambush" (Middle English Dictionary; see lurk), or it may be from Old French lourche, from Middle High German lurz "left," also "wrong" [OED]. The immediate source of the transferred use in leave in the lurch "leave suddenly and unexpectedly in an embarrassing predicament" (1590s) would be cribbage.

lurch (v.)

1821, "to roll or sway suddenly to one side," from lurch (n.1). Meaning "walk with an uneven gait" is from 1851. Related: Lurched; lurching.