Hiccough: Hiccups happen when the diaphragm, the muscle that separates the chest from the abdomen, suddenly contracts. When that happens, air is taken in, and then the voice box closes shut, which is what causes the "hic" sound. There are different types of hiccups, named after how long they last:
A "regular" bout of hiccups can last up to 48 hours
"Persistent hiccups" last longer than 48 hours and up to a month
"Intractable hiccups" last longer than a month
Alternative terms for "hiccough" and "hiccups" include: "hickup" and "singultus".