In phonetics, a stop which is both ingressive and glottalic. What this means in detail is that as well as a temporary stoppage somewhere in the mouth (making it a B or D or G or whatever, depending on where that primary stoppage is), there is also a stoppage of the glottis (in the larynx), which is moved briefly downward to rarefy the trapped air. The glottis being then released, the trapped air moves downward, causing a characteristic hollow resonance.

In Bantu languages such as Swahili, the sounds B D J and G are normally made implosively, except when in the clusters MB ND NJ and NG. In the Nigerian language Hausa there are implosives b and d. As there are also normal (plosive) b and d, the implosive ones are written in their alphabet with the top of the letter curling over to the right.

Because the mouth cavity is at lower pressure, and the glottal closure cannot be made complete, air from the lungs continues to push at the larynx and permeates through it, causing voice, i.e. vibration of the glottis. So implosives are voiced B D G; contrast this with ejectives P' T' K', made similarly but with release in the opposite direction.