spillway (n.)

Old English spillan "destroy, mutilate, kill," also in late Old English "to waste," variant of spildan "destroy," from Proto-Germanic *spilthjan (source also of Old High German spildan "to spill," Old Saxon spildian "destroy, kill," Old Norse spilla "to destroy," Danish spilde "lose, spill, waste," Middle Dutch spillen "to waste, spend"), from a probable PIE root *spel- (1) "to split, break off" (source also of Middle Dutch spalden, Old High German spaltan "to split;" Greek aspalon "skin, hide," spolas "flayed skin;" Latin spolium "skin, hide;" Lithuanian spaliai "shives of flax;" Old Church Slavonic rasplatiti "to cleave, split;" Middle Low German spalden, Old High German spaltan "to split;" Sanskrit sphatayati "splits").

Sense of "let (liquid) fall or run out" developed mid-14c. from use of the word in reference to shedding blood (early 14c.). Intransitive sense "to run out and become wasted" is from 1650s. Spill the beans recorded by 1910 in a sense of "spoil the situation;" 1919 as "reveal a secret." To cry for spilt milk (usually with negative) is attested from 1738. Related: Spilled; spilt; spilling.

Old English weg "road, path; course of travel; room, space, freedom of movement;" also, figuratively, "course of life" especially, in plural, "habits of life" as regards moral, ethical, or spiritual choices, from Proto-Germanic *wega- "course of travel, way" (source also of Old Saxon, Dutch weg, Old Norse vegr, Old Frisian wei, Old High German weg, German Weg, Gothic wigs "way"), from PIE root *wegh- "to go, move, transport in a vehicle."

From c. 1300 as "manner in which something occurs." Adverbial constructions attested since Middle English include this way "in this direction," that way "in that direction," both from late 15c.; out of the way "remote" (c. 1300). In the way "so placed as to impede" is from 1560s.

From the "course of life" sense comes way of life (c. 1600), get (or have) one's way (1590s), have it (one's) way (1709). From the "course of travel" sense comes the figurative go separate ways (1837); one way or (the) other (1550s); have it both ways (1847); and the figurative sense of come a long way (1922).

Adverbial phrase all the way "completely, to conclusion" is by 1915; sexual sense implied by 1924. Make way is from c. 1200. Ways and means "resources at a person's disposal" is attested from early 15c. (with mean (n.)). Way out "means of exit" is from 1926. Encouragement phrase way to go is short for that's the way to go.