This is very economical of space and involves a clever computer ploy, but it does not provide a particularly useful synonym dictionary, for, as we all know, synonymy in language does not yield to the commutative law of mathematics; in language, Things equal to the same thing are not ( necessarily ) equal to each other. Perhaps the Proximity people thought that they had got round that little problem by giving the same definition for each of the items in the list; but we know that only very rarely are two synonyms bi-unique ( which is another way of saying that if A = B, B does not necessarily always equal A ), an ineluctable fact of language.
In language, things equal to the same thing may not be equal to each other.  The Proximity of people thought that they had gotten around that problem by giving the same definition for each item on a list, but we know that only very rarely are two synonyms bi-unique.