Usually a continuum refers to a whole, no part of which can be distinguished from neighboring parts except by arbitrary division.

See:

• Continuum (mathematics) - sets such as the real line
• Continuum hypothesis - "There is no set whose size is strictly between that of the integers and that of the real numbers."
• Continuum mechanics, branch of physics that deals with continuous matter, including both solids and fluids.
• The Spacetime
• The computer game Continuum aka Subspace.
• Language continuum
• Continuum is also the name of a publisher