"fireman's scaling ladder," short for pompier ladder (by 1893), French, literally "fireman," from pompe "pump" (see pump (n.1)).
1650s, "resembling a ladder," from Latin scalaris "of or pertaining to a ladder," from scalae (plural) "ladder, steps, flight of steps" (see scale (n.2)). The noun in the mathematical sense of "a real number" is from 1846, coined by Irish mathematician William R. Hamilton (1805-1865), who can explain why it is the correct word for that.
"a truck; a long wagon with a flat bed and four wheels," 1838, British railroad word, probably from verb lurry "to pull, tug" (1570s), which is of uncertain origin. Meaning "large motor vehicle for carrying goods on roads" (equivalent of U.S. truck (n.1)) is first attested 1911.
recreational pastime of riding a river on a truck tire inner tube, 1975; see tube (n.).
"covered truck or wagon," 1829, shortening of caravan. Century Dictionary suggests this was perhaps regarded as *carry-van.
"to climb (a wall) by or as by a ladder; attack with scaling ladders," late 14c., scalen, from Latin scala "ladder, flight of stairs," from *scansla, from stem of scandere "to climb" (see scan (v.)).
Middle English scale, "ladder used in sieges," is attested c. 1400, from the Latin noun. The verb in general and figurative use (of mountains, heights of pleasure, etc.) is from 16c.
Via scale (n.3) "standard of measure or estimation" comes the meaning "measure or regulate by a scale" (1798), the sense of "draw, project, or make according to scale" (by 1885), and scale down "cut or decrease proportionally in every part" (by 1887). Related: Scaled; scaling.
1776, "to stab," from jack-knife (n.). Intransitive meaning "to fold or bend" the body is said to date from the time of the American Civil War. The truck accident verbal sense is from 1949. Related: Jackknifed; jackknifing.
Old English stigel, stile "device for climbing, ladder," related to stigen "to climb," from Proto-Germanic *stig- "to climb" (see stair). An arrangement to allow persons to pass but not sheep and cattle.