1. Repeated involuntary spasms of the diaphragm followed by sudden closures of the glottis, which checks the inflow of air and produces the characteristic sound.
2. An extraordinary type of breathing movement that involves a sudden intake of air, or inspiration, due to a sudden involuntary contraction of the diaphragm, accompanied by the closure of the glottis (opening between the vocal cords) in the larynx (vocal cords area).

The closure of the glottis then halts the incoming air and the column of air strikes the closed glottis to produce the characteristic sounds of hiccups.

Transient episodes are common; while "persistent hiccups" (up to two days) and "intractable hiccups" (up to one month) are uncommon and quite distressing for the person who is experiencing the condition.

Singultus is "medicalese" for "hiccup" and comes from a Latin element that means "a gasp" or "a sob"; especially, those which are repeated.

The state of having reflex spasms of the diaphragm accompanied by a rapid closure of the glottis producing an audible sound; sometimes a symptom of indigestion.

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. They are usually 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.