semi-trailer
UK[ˌsemi ˈtreɪlə(r)]US[ˌsemi ˈtreɪlər, ˌsɛmaɪ-]
n
A large trailer that is supported at the front by the towing vehicle and has wheels only at the rear.
n
The combination of a tractor unit and such a trailer.
Morpheme Breakdown
semi
trailer
semi
half
trailer
vehicle towed behind another
Etymology
The word 'semi-trailer' is a modern compound that logically describes the vehicle's functional design. The prefix 'semi-', from Latin 'semi-' meaning 'half', indicates that this type of trailer is only partially self-supporting, as its front end rests on the tractor unit. The second element, 'trailer', originates from the action of 'trailing' or being pulled behind, a concept with Germanic roots. Combined, the term precisely denotes a freight-carrying vehicle that is half-supported by its own rear wheels and half-supported by the power unit that tows it, distinguishing it from a full trailer with front and rear axles.
Analysis
Structure: semi (half) + trailer (vehicle towed behind another)
semi: Latin origin, meaning 'half'. In English, it functions as a prefix denoting partial, incomplete, or halfway status.
trailer: Derived from the verb 'trail' (to draw or drag along behind) + the agent noun suffix '-er'. It is of Germanic origin via Middle English and Old English.
Examples
The highway was temporarily closed after a semi-trailer overturned, spilling its cargo.
He drives a semi-trailer across the country, delivering goods from coast to coast.
The logistics company is expanding its fleet with fifty new semi-trailers.