Glottal consonants are
consonants articulated with the
glottis. Many phoneticians consider them, or at least the so-called fricatives, to be transitional states of the glottis without a point of articulation as other consonants have; in fact, some do not consider them to be consonants at all. However, the glottal stop at least behaves as a typical consonant in languages such as
Tsou.
See more at Wikipedia.org...