semi vs trailer truck

semi and trailer truck both are nouns.

Word	Noun	Adjective	Verb	Adverb
semi	Yes	No	No	No
trailer truck	Yes	No	No	No

As nouns, semi and trailer truck are synonyms defined as:

semi and trailer truck: a truck consisting of a tractor and trailer together

Other synonyms of semi include articulated lorry, rig, tractor trailer, trucking rig.

semi (noun)	trailer truck (noun)
a trailer having wheels only in the rear; the front is supported by the towing vehicle	a truck consisting of a tractor and trailer together
a truck consisting of a tractor and trailer together
one of the two competitions in the next to the last round of an elimination tournament