Hiccough: A hiccough is an extraordinary type of breathing movement involving a sudden intake of air (inspiration) due to an involuntary contraction of the diaphragm accompanied by closure of the vocal apparatus (glottis) of the larynx. A hiccough is also called a hiccup.
The abrupt inspiration is the result of a sudden contraction of the diaphragm. Closure of the glottis then halts the incoming air. The column of air strikes the closed glottis to produce the characteristic sound: a hiccup.
Hiccups are often rhythmic. If self-limited, they are just a minor nuisance, but prolonged hiccups can become a major medical problem.
The word "hiccup" was in use by 1530. It is an instance of onomatopoeia, the imitation of natural sounds by words. Alternative terms for "hiccough" and "hiccups" include "hickup" and "singultus".