Elasticsearch synonym analyzer not working
The order of the filters is
filter":[ "lowercase", "synonym_filter"]So, if elasticsearch is "lowercasing" first the tokens, when it executes the second step, synonym_filter, it won't match any of the entries you have defined.
To solve the problem, I would define the synonyms in lower case
You can also define your synonyms filter as case insensitive:
"filter":{ "synonym_filter":{ "type": "synonym", "ignore_case" : "true", "synonyms":[ ... ] } }