GC: n

S: WHO – https://bit.ly/2WhCgO3 (last access: 2 June 2019); MEDNT – https://bit.ly/2C4YW5h (last access: 2 June 2019).

N: 1. “incapacity of distinguishing or perceiving sounds,” late 14c., defnesse, from deaf + -ness.
2. Deafness, partial or total inability to hear. The two principal types of deafness are conduction deafness and nerve deafness. In conduction deafness, there is interruption of the sound vibrations in their passage from the outer world to the nerve cells in the inner ear. The obstacle may be earwax that blocks the external auditory channel, or stapes fixation, which prevents the stapes (one of the minute bones in the middle ear) from transmitting sound vibrations to the inner ear. In nerve deafness, some defect in the sensory cells of the inner ear (e.g., their injury by excessive noise) or in the vestibulocochlear nerve prevents transmission of sound impulses from the inner ear to the auditory centre in the brain. Deafness at birth is nearly always of the nerve type and cannot be improved by medical means.
3. A loss of the ability to hear without designation of the degree of loss or the cause.

S: 1. OED – https://bit.ly/2HPCPWd; https://bit.ly/2Wpd5sY; https://bit.ly/2IcBdF3 (last access: 2 June 2019). 2. EncBrit – https://bit.ly/2YZhjnK (last access: 2 June 2019). 3. TERMIUM PLUS – https://bit.ly/2Iitt4f (last access: 2 June 2019).

SYN:
S:

CR: anacusis, hypoacusis.