Idioms are phrases which cannot be understood simply by looking at the meaning of the individual words in the phrase.
Idiom:
bite off more than one can chew
Meaning:
to try to do more than one is able to do
Example:
I bit off more than I can chew by agreeing to do another assignment.
List of common idioms, their meanings and examples of their usage in sentences
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.