Sentence:  <WSD>Modules</WSD> over a ring are a generalization of abelian groups (which are <WSD>modules</WSD> over \textstyle\mathbb{Z}). 
Meaning of the word marked with <WSD> tags:  An abelian group equipped with the operation of multiplication by an element of a ring (or another of certain algebraic objects), representing a generalisation of the concept of "vector space" with "scalar multiplication".