18-wheeler
noun
- a trucking rig consisting of a tractor and a trailer and typically having eighteen wheels
Wiktionary
noun
Etymology: From the total number of wheels: two front steering wheels on the tractor, plus dual wheels on each end of two axles (total of 8) at the rear of the tractor and supporting the front of the trailer, plus dual wheels on two axles at the rear of the trailer.
- A big rig truck: a semi-trailer plus the truck or tractor pulling it.
“On a cold morning in Abilene, Texas, a column of 18-wheelers crawls down bumpy, waterlogged roads, past cattle grazing on dusty shrubs.”