Words which have multiple meanings, but the meanings are all related.
For eg: issue
“Issue a book”
“They have decided not to have any issues”
“The last issue of India Today”
“Lovely smells issued from my neighbour’s kitchen”
“Of course I’ll help you, don’t make an issue out of it.”
There is one ‘sense’ of the word issue, relating to origin, or making something. This is the sense used in an issue of a magazine, or issue used to refer to someone’s child.
Then there is the other ‘sense’, where it means some problem.
Within these two senses itself too, you have different meanings of issue, but they exhibit polysemy, since in “issue a book” and “smells issued from”, the meaning is not exactly the same, however closely related.
However the meaning of issue as “problem” may not be thought to be closely related to these uses.
Another example would be the word ‘gay’, meaning either “happy” or “homosexual”.
There are two types of synonymy, absolute, and near. Absolute synonymy