An easy way to know the definition of intermolecular forces is by breaking the word into parts. The word 'inter' means inbetween two things. Therefore, intermolecular forces means the attraction felt between atoms and molecules.you should also know that intermolecular forces differ from chemical bonds for breaking a chemical bond creates new material that differently reacts with other elements while breaking an intermolecular attraction does not change the chemical formula or reactivity. This doesn't mean that theses attractions have no function in chemistry. These forces are able to determine if a reaction can occur and the rate at which this reaction can occur. They can also determine the state of a material at a given temperature. Some examples are: triethyl amine in acetone, water, acetone in water, ...