Word forms: (regular plural) semitrailers
noun (Automotive engineering: Vehicle types) A semitrailer is the long rear section of a truck that can bend when it turns. ⇒ The truck driver was slightly injured when his semitrailer overturned. ⇒ Heavy trucks and semitrailers account for about 15 percent of all traffic along the highway, yet make up 25 percent of all vehicles involved in fatal crashes. ⇒ Traffic was halted for an hour in the snow after several semitrailers that had stopped to put on chains had trouble getting going again.
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