Synonyms can be used to expand or contract.
expand: jump becomes skip and hop too
contract: jump and skip are normalized to hop.
In the case of expansions you need only apply the synonym analyzer to the docs at index time or the queries at query time.
Index-time expansion = faster queries but requires reindexing when synonyms change
Query-time expansion = slower queries and no need to reindex when synonyms change
For contraction use cases the queries and indexed docs both need to be in agreement in what to normalize words to and so changes to synonyms require a reindex.