semi vs motortruck

semi and motortruck both are nouns.

Word	Noun	Adjective	Verb	Adverb
semi	Yes	No	No	No
motortruck	Yes	No	No	No

As nouns, motortruck is a hypernym of semi; that is, motortruck is a word with a broader meaning than semi:

Other hypernyms of semi include truck.

semi (noun)	motortruck (noun)
a trailer having wheels only in the rear; the front is supported by the towing vehicle	an automotive vehicle suitable for hauling
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