Boil can mean:

• to bring to the boiling point, at which a substance goes from the liquid to the gaseous phase.
• to cook in boiling water
• a localized accumulation of pus in the skin, resulting from infection; see boil.
• to convert printed data (books, journals and so on) to digital format using a scanner. This use originates from the way that people use steam to melt glue which binds pages when they disassemble a book to scan.
• a disturbance on the water surface of a river or estuary, often caused by the presence of a bar or dune on the riverbed.

Boil