If you mean an English word synonym:
Synonyms for synonym
noun:
analogue
equivalent
metonym
equivalence:
adequation
agreement
alikeness
compatibility
conformity
correlation
correspondence
equality
evenness
exchangeability
identity
interchangeability
interchangeableness
likeness
match
par
parallel
parity
synonym
synonymy
Then there is no "standard functionality" for that - you will have to find a suitable webservice, API, or website and get the information from there.