An expression in the usage of a language that is peculiar to itself either in having a meaning that cannot be derived from the conjoined meanings of its elements or in its grammatically atypical use of words.
take the initiative to (do something)
to decide to do something although one has not been asked to do it
I decided to take the initiative to organize a dinner for my friend who was leaving to go to a different university.
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.