from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A semitrailer.
  • noun A tractor-trailer.
  • noun A semifinal.
  • noun A semiformal dance.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun UK, Australia, Canada A semi-detached house.
  • noun A semitrailer; a tractor-trailer; an eighteen-wheeler.
  • noun A semifinal.
  • noun slang A partial erection.


from Wiktionary, Creative Commons Attribution/Share-Alike License

The prefix semi- (from Latin) used as a noun.


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  • UK slang for a partially erect penis.

    December 24, 2008

  • I've never heard that one before; hopefully it's still safe to use semi for semi-final and semi-detached.

    December 25, 2008

  • I've heard people use the expression half-on (sounds like a play off hard-on) for this.

    December 25, 2008

  • The main use in British English is to describe a semi-detached house, often of Tudorbethan style. Sandi Toksvig, a BBC presenter of multiple talents, came out of the closet in the mid-1990s, and was dropped like a hot potato by Save the Children, for whom she acted as a sort of ambassador. She exploited this to comedic effect in a stand-up routine, in which she recounted her mother's reaction to the whole hullabaloo: "It's terrible what they said about you in the press! I just can't believe it. They called your house a semi!"

    December 25, 2008