An idiom is a group of words, or in other words, a phrase that has a meaning other than its literal meaning of the words in it.
talk (someone) down in price
to convince someone to lower the price of something
I was able to talk the man down in price when I was buying the stereo.
List of common idioms, their meanings and examples of their usage in sentences
An idiom is defined as - a group of words in a fixed order that has a particular meaning that is different from the meanings of each word on its own.