Idioms are phrases which cannot be understood simply by looking at the meaning of the individual words in the phrase.
sweet and sour
a combination of sweet and sour tastes (found in many Chinese dishes)
The dish had a sweet and sour taste that was very delicious.
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.