continuous spectrum

The term continuous spectrum (or continuum) refers to a spectrum or portion of a spectrum that is smooth, i.e., with no spectral lines or other discontinuities like the Balmer jump. Black-body radiation ideally has such a continuous spectrum. The term is also used to refer to the spectrum on either side of a specific spectral line, or what the spectrum would be without that line, used in describing the line's depth or shape. Often underlying a spectrum is a continuous spectrum with an overall shape (e.g., a black-body spectrum), the actual spectrum also including spectral lines and bands. The term discrete spectrum refers to an unsmooth spectrum, e.g., with such lines.