v.1. To cause something to fall upon or come into contact with something: The moon cast its light on the snowy countryside.
2. To cause or give rise to some critical valuation about something or someone: These facts cast doubt on the suspect's story.
3. To make the first row of stitches in knitting by putting some number of stitches on a knitting needle: Be careful not to cast on too tightly or it will be difficult to knit the first row. Start by casting on 18 stitches. Make 4 loops and cast them on.