Nucleophilic Substitution with ammonia helpWatch
Well its seems like our perceptions of adducts are different.
Either my inorganic chemistry lecturer is lying or....... well she isn't.
The compound would be described as water forming an adduct with the magnesium sulphate, and the whole compound would not be called an adduct, instead it would be called by its name as hydrated magnesium sulphate.
Having said that, thanks for correcting me earlier on.
Definition of adduct
A new chemical species AB, each molecular entity of which is formed by direct combination of two separate molecular entities A and B in such a way that there is change in connectivity, but no loss, of atoms within the moieties A and B. Stoichiometries other than 1:1 are also possible, e.g. a bis-adduct (2:1). An "intramolecular adduct" can be formed when A and B are groups contained within the same molecular entity .
This is a general term which, whenever appropriate, should be used in preference to the less explicit term complex. It is also used specifically for products of an addition reaction. For examples see Lewis adduct, Meisenheimer adduct, -adduct.
Edit: though maybe the magnesium sulphate isn't a molecular entity, the Gold Book isn't very helpful
although I cannot comment on the Diels Alder reactions (haven't studied that at uni yet), it does seem like the definition of adducts vary (a little bit) from reaction to reaction.