My peeve is the claim that the most nearly perfect synonyms in English are "gorse" and "furze."

I have two reasons.

1. if true, I don't know the name of the genius who first made this observation out of an English lexicon of hundreds of thousands of words, and

2. if false, the claim is smugly pretentious.

It may be true, however. Merriam-Webster defines "gorse" and "furze" identically:

"a spiny yellow-flowered European shrub (Ulex europaeus) of the legume family ...[or] any of several related plants (genera Ulex and Genista)"

So "gorse" and "furze" are exact synonyms. But that's just point one. Besides being semantically interchangeable (like many other synonyms), the words are formally and dialectically similar.

Both are one-syllable words of five letters. Both contain an "r" and both end in a silent "e." What's more, both are perfectly acceptable at all stylistic levels (neither, for example is slang or poetic), and neither is geographically localized.

Finally - as icing on the cake - both descend from Old English, when they were already exactly synonymous.

What other synonyms can make these boasts?

There's a third Ulex synonym, "whin," but, besides having just four letters (none of which appear in either "gorse" or "furze"), regrettably doesn't appear till the 14th century. (Nice try, though.)

So what genius did first discover the unique degree of synonymy between "gorse" and "furze"?