Corn syrup is a food syrup

Syrup

In cooking, a syrup is a thick, viscous liquid consisting primarily of a solution of sugar in water, containing a large amount of dissolved sugars but showing little tendency to deposit crystals...

, which is made from the starch

Starch

Starch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store...

 of maize

Maize

Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...

 and contains varying amounts of maltose

Maltose

Maltose , or malt sugar, is a disaccharide formed from two units of glucose joined with an αbond, formed from a condensation reaction. The isomer "isomaltose" has two glucose molecules linked through an α bond. Maltose is the second member of an important biochemical series of glucose chains....

 and higher oligosaccharide

Oligosaccharide

An oligosaccharide is a saccharide polymer containing a small number of component sugars, also known as simple sugars...

s, depending on the grade. Corn syrup is used in foods to soften texture, add volume, prevent crystallization of sugar, and enhance flavor. Corn syrup is distinct from high-fructose corn syrup (HFCS), which is created when corn syrup undergoes enzymatic processing, producing a sweeter compound that contains higher levels of fructose

Fructose

Fructose, or fruit sugar, is a simple monosaccharide found in many plants. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into the bloodstream during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847...

.

The more general term glucose syrup

Glucose syrup

Glucose syrup is a food syrup, made from the hydrolysis of starch. Maize is commonly used as the source of the starch in the USA, in which case the syrup is called "corn syrup", but glucose syrup is also made from other starch crops, including potatoes, wheat, barley, rice and cassavap.21...

 is often used synonym

Synonym

Synonyms are different words with almost identical or similar meanings. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy. The word comes from Ancient Greek syn and onoma . The words car and automobile are synonyms...

ously with corn syrup, since glucose syrup is in the US most commonly made from corn starch.