(1) "Exclusive breastfeeding" is defined as no other food or drink, not even water, except breast milk for at least 4 and if possible 6 months of life, but allows the infant to receive drops and syrups (vitamins, minerals and medicines). "Predominant breastfeeding" means that the infant's predominant source of nourishment has been breast milk. However, the infant may also have received water and water-based drinks (sweetened and flavoured water, teas, infusions, etc), fruit juice, or ORS solution.
http://www.who.int/nutrition/topics/.../en/index.html