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:
open up on (someone or something)
Meaning:
to attack someone or something, to fire a gun or other weapon at someone or something
Example:
The man with the gun opened up on the people on the bus.
List of common idioms, their meanings and examples of their usage in sentences
An idiom is a group of words, or in other words, a phrase that has a meaning different from the literal meaning of the words in it.