- The Corrective Optics Space Telescope Axial Replacement (COSTAR) was the instrument designed to correct Hubble Space Telescope's spherical aberration for light focused at the FOC, FOS and GHRS instruments. Built by Ball Aerospace Corp. ...
- CoStar Group, Inc. is one of the largest providers of information/marketing services to commercial real estate professionals in the United States as well as the United Kingdom. ...
- A person who shares star billing; A person who slightly lacks the status to be considered a star; To perform with the billing of a costar
- Taiwanese manufacturer of the Das Keyboard.