In electrical engineering and acoustics, immittance is a concept combining the impedance and admittance of a system or circuit. The term immittance was invented by Bode.

It is sometimes convenient to use immittance to refer to a complex number which may be either the impedance (ratio of voltage to current in electrical circuits, or sound pressure to volume velocity in acoustical systems) or the admittance (ratio of current to voltage, or volume velocity to sound pressure) of a system. In audiology, tympanometry is sometimes called immittance testing.