An optical instrument used for spectrographic analysis .

(physics) The portion of the electromagnetic spectrum that is visible to humans. / (physics) an extension of the human-visible spectrum to include near-visible wavelengths, primarily near infrared.

(analytical chemistry) Of or relating to spectroscopy or to a spectroscope.

(astronomy) A classification of stars depending on their spectra and luminosity; usually one of O, B, A, F, G, K, M.

A visual representation of the spectrum of a sound changing through time. / (astronomy) A visual representation of the spectrum of a celestial body's radiation.

A machine for recording spectra, producing spectrograms.

(physics) a dark or bright line in an otherwise continuous spectrum caused by the absorption or emission of light, at a single wavelength, by the movement of electrons between energy levels of an atom or molecule

(physics) The portion of the electromagnetic spectrum which is visible to the human eye (red, orange, yellow, green, blue, and violet).

(pharmacology) Any antibiotic that is active against a wide range of bacteria, especially against both gram-positive and gram-negative bacteria.

(physics) Any of several series of spectral lines of hydrogen that correspond to quantum transitions between the various allowed energy levels of the hydrogen atom.