"...there is no such thing as a true synonym."

The use of a human natural language is a matter of agreement between people and names of things (words) are arbitrarily given to objects. Such names are meant to identify things, etc. and are therefore unique identifiers at the start, though may be longer than a single word. Hence you need disambiguation in defining the meaning of wikipedia entry words too. So what you have is a list of words that may replace each other subject to various contextual circumstances.

"Those who work with language know that there is no such thing as a true synonym.Even though the meanings of two words may be the same - or nearly so - there are three characteristics of words that almost never coincide: frequency, distribution and connotation."1

This is well reflected in various new English dictionaries where you find frequency data next to a dictionary entry, etc.

One of the major achievements in lexicography belongs to a Hungarian translator Tibor Bartos, who compiled his Magyar szótár by claiming the very same idea as above.

Laurence Urdang in the Introduction to The Synonym Finder