Idioms
An idiom is a type of phrase or expression that has a meaning that can't be deciphered by defining the individual words.
Idiom:
on horseback
Meaning:
on the back of a horse
Example:
We went to the campground on horseback.
List of common idioms, their meanings and examples of their usage in sentences
A group of words which have a different meaning when used together from the one they would have if you took the meaning of each word separately.