Definition of "semi" in English

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.

2. (Australia, Canada, New Zealand, US) A semi-trailer; a tractor-trailer; an eighteen-wheeler; an artic.

3. (informal) A semifinal.

4. (slang) A partial erection of the penis.

5. (slang) A semiautomatic firearm.

6. (slang, finance) Semiconductor companies or positions in the stock market.

7. (colloquial, mining) An intermediate in the production of end-use goods.

adverb

1. (informal) Somewhat; to some extent.