Water reactivity

A reactivity issue of a group of organic reactions that take place as an emulsion in water and that exhibit unusual reaction rate acceleration compared to the same reaction in an organic solvent or compared to the corresponding dry media reaction
Reference: Chemical Process Safety – Fundamentals with Applications, 2nd Ed., Daniel A. Crowl/Joseph F. Louvar
A substance presents reaction with water if a clear, intense, and usually very quick, exothermal reaction is observed when the substance is put in contact with water.
Reference: S2S (safety to safety website)
Science/Chemical Reactivity/Reactive Interactions