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An object's infrared excess (IRX) is additional infrared EMR beyond what is expected, e.g., that of a typical stellar spectrum or a black-body spectrum. An IRX is a sign of intervening matter contributing its own black body spectrum. In the case of a star, that could be something surrounding it such as a circumstellar disk (such as around a pre-main-sequence star) or circumstellar envelope (around an asymptotic giant branch star). IRX quantification is often carried out using a color index, e.g., comparing V with an infrared passband.
The term infrared excess is definitely used for stars; the concept definitely also applies for other objects: galaxies can be similarly affected when dust obscures an active galactic nucleus or star formation, leading to extra infrared, e.g., those termed dusty galaxies or luminous red galaxies. Possibly the term infrared excess has also been used in such other cases.