I was wondering why semi-trucks are called that. Doesn’t semi mean “part of”? A semi-truck is a whole truck if I ever saw one!


Semi truck or semi is short for semi-trailer truck.¹ The prefix semi- literally means half.² The term describes a truck consisting of a tractor and a semi-trailer. A semi-trailer is semi-supported (half supported) by its own wheels, which support only the rear of the trailer. The front of the trailer is supported by the rear wheels of the tractor.³

picture of a semi-trailer truck

  • Yes, see this link for more explanation. – Jim Aug 2 '12 at 0:12
  • 2
    AKA "tractor trailer" – Bob Aug 2 '12 at 1:14
  • 2
    In Australia we call the pictured contraption (including the truck body) a "semi-trailer", and the truck/tractor bit when referred to separately a "prime mover". – John Lyon Aug 2 '12 at 6:39
  • 3
    And in the UK this is called an "articulated lorry", or sometimes just an "artic". – Martin Aug 2 '12 at 7:44
  • 1
    @Martin: or Juggernaut! – e100 Aug 2 '12 at 10:32

protected by Mari-Lou A Jun 9 '14 at 7:01

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.