In
phonetics this refers to sounds whose
articulation is affected by closing the back of the
tongue against the
velum (the soft
palate), and altering the shape of the tongue to create
compression or
rarefaction of the air trapped in the mouth, so that it sounds different when it is released. In fact compression is never used in language. The only velaric sounds that occur are with rarefied mouth
cavity, the so-called
clicks of southern African languages.
Note that this term is different from velar, which means that the primary closure is at the velum. Velar sounds include k and g, and are very common. A velaric sound has a closure elsewhere with a secondary closure at the velum.