from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Informal A combination of a tractor and a semitrailer; a tractor-trailer rig.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A tractor-trailer with eighteen wheels, normally with two steerable wheels on the first axle and four wheels on two fixed axles of the tractor and two fixed four-wheel axles on the rear of the trailer.
Sorry, no etymologies found.