The words 'happy' and 'joyful' are close synonyms.
exact synonym
Frequency:
60
%
In this context, 'big' is an exact synonym for 'large'.
perfect synonym
Frequency:
45
%
In linguistics, there is no such thing as a perfect synonym.
opposite synonym
Frequency:
30
%
In this case, 'hot' is the opposite synonym of 'cold'.
Idiomatic Expressions for synonymy
Phrase: synonymy of ideas
Meaning: the concept of having interchangeable or closely related ideas
Usage: The philosopher discussed the synonymy of ideas in his latest book.