Singultus

A rarely used medical word for an ordinary hiccup.

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.