From Distillers Wiki
The term can also mean the substance or quality that imparts identity to a particular thing or the essence.
A juice may be supplied in concentrate form, requiring the user to add water to re-constitute the liquid back to the original state. A juice will usually have a defined level of purity, in some countries of 100%. It should not be confused with a squash which is usually an artificial juice to be diluted with water.
In slang fruit juice refers to an alcoholic drink.