bobtail

Short definition from Wiktionary

Noun

1. 1
   A short, or deliberately shortened tail.
2. 2
   An animal that has a bobtail, such as certain canines or nags.
3. 3
   A tractor which performs without its trailer.
4. 4
   A tractor-trailer that is relatively short in length.
5. 5
   A tractor-trailer that is relatively short in length: The tractor unit of a semi-truck without a trailer.
6. 6
   An open-ended straight or four flush.
7. 7
   A bobtail squid.
8. 8
   A bobtail skink.

Verb

1. 1
   To drive a tractor without its trailer.
2. 2
   To drive a truck or other vehicle without its trailer.