semi

Etymology

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

noun

1. (UK, Ireland, Australia, Canada, informal) A semi-detached house.
   2008, Elliott Placks, quoted in Helen Isbister, Morris Bryant, Property, Career FAQs, Australia, page 40, I′m selling two side-by-side semis that are currently under construction, a waterfront apartment and a house in Rose Bay.
   The smaller semis of the 1920s and 1930s were closely related to the three bedroom pre-1919 narrow fronted terraces, at least to the larger pre-1919 terraces. 2008, Barry Goodchild, Homes, Cities and Neighbourhoods: Planning and the Residential Landscapes of Modern Britain, page 52
2. (Australia, Canada, New Zealand, US) A semi-trailer; a tractor-trailer; an eighteen-wheeler; an artic.
   I was hungry an' freezin' an' done caught a chill / When the lights of a big semi topped the hill 1967, Tommy Faile (lyrics and music), “Phantom 309”, performed by Red Sovine
   All night we couldn′t hear each other speak because of the sound of semis changing gear to get over the hill. 2011, Eamonn Duff, Schapelle Corby: The Untold Story Behind Her Ill-Fated Drug Run, Australia: Allen & Unwin, unnumbered page
3. (informal) A semifinal.
4. (slang) A partial erection of the penis.
   The twink got a semi just from that look. 2010, Mickey Erlach, Video Boys, page 158