The term 'Behemoth Highway' is composed of four crossword solutions: SEMI (4 letters), TRUST (5 letters), HIPPO (5 letters), and TITANOSAUR (10 letters). SEMI is a shortened form of the word 'SEMI-trailer, ' which is a large truck with a trailer attached to it. TRUST is a noun that means a firm belief in the reliability, truth, or ability of someone or something. HIPPO is an abbreviation for the word 'HIPPOPOTAMUS, ' which is a large mammal native to Africa. Finally, TITANOSAUR is a type of dinosaur that lived during the late Cretaceous period and was one of the largest land animals ever to exist.