The "reverse dictionary" is called a "thesaurus". Wikipedia quotes Peter Mark Roget (1852):

> ...to find the word, or words, by which [an] idea may be most fitly and aptly expressed

Digital reverse dictionaries / thesauri like https://www.onelook.com/thesaurus/ can take natural language input, and afaict are strictly better at this task than LLMs. (I didn't know these tools existed when I wrote the rest of this comment.)

I briefly investigated LLMs for this purpose, back when I didn't know how to use a thesaurus; but I find thesauruses a lot more useful. (Actually, I'm usually too lazy to crack out a proper thesaurus, so I spend 5 seconds poking around Wiktionary first: that's usually Good Enough™ to find me an answer, when I find an answer I can trust it, and I get the answer faster than waiting for an LLM to finish generating a response.)

There's definitely room to improve upon the traditional "big book of synonyms with double-indirect pointers" thesaurus, but LLMs are an extremely crude solution that I don't think actually is an improvement.

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yunwal 4 hours ago | parent | next [-]

A thesaurus is not a reverse dictionary

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dgacmu 4 hours ago | parent | prev [-]

Really?

"What's a word that means admitting a large number of uses?"

That seems hard to find in a thesaurus without either versatile or multifarious as a starting point (but those are the end points).

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wizzwizz4 4 hours ago | parent [-]

I plugged "admitting a large number of uses" into OneLook Thesaurus (https://www.onelook.com/thesaurus/?s=admitting%20a%20large%2...), and it returned:

> Best match is versatile which usually means: Capable of many different uses

with "multi-purpose", "adaptable", "flexible" and "multi-use" as the runner-up candidates.

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Like you, I had no idea that tools like OneLook Thesaurus existed (despite how easy it would be to make one), so here's my attempt to look this up manually.

"Admitting a large number of uses" -> manually abbreviated to "very useful" -> https://en.wiktionary.org/wiki/useful -> dead end. Give up, use a thesaurus.

https://www.wordhippo.com/what-is/another-word-for/very_usef..., sense 2 "Usable in multiple ways", lists:

> useful multipurpose versatile flexible multifunction adaptable all-around all-purpose all-round multiuse multifaceted extremely useful one-size-fits-all universal protean general general-purpose […]

Taking advantage of the fact my passive vocabulary is greater than my active vocabulary: no, no, yes. (I've spuriously rejected "multipurpose" – a decent synonym of "versatile [tool]" – but that doesn't matter.) I'm pretty sure WordHippo is machine-generated from some corpus, and a lot of these words don't mean "very useful", but they're good at playing the SEO game, and I'm lazy. Once we have versatile, we can put that into an actual thesaurus: https://dictionary.cambridge.org/thesaurus/versatile. But none of those really have the same sense as "versatile" in the context I'm thinking of (except perhaps "adaptable"), so if I were writing something, I'd go with "versatile".

Total time taken: 15 seconds. And I'm confident that the answer is correct.

By the way, I'm not finding "multifarious" anywhere. It's not a word I'm familiar with, but that doesn't actually seem to be a proper synonym (according to Wiktionary, at least: https://en.wiktionary.org/wiki/Thesaurus:heterogeneous). There are certainly contexts where you could use this word in place of "versatile" (e.g. "versatile skill-set" → "multifarious skill-set"), but I criticise WordHippo for far less dubious synonym suggestions.

	▲	dgacmu 3 hours ago \| parent [-]
		'multifarious uses' -> the implication would be having not just many but also a wide diversity of uses M-W gives an example use of "Today’s Thermomix has become a beast of multifarious functionality. — Matthew Korfhage, Wired News, 21 Nov. 2025 " wordhippo strikes me as having gone beyond the traditional paper thesaurus, but I can accept that things change and that we can make a much larger thesaurus than we did when we had to collect and print. thesaurus.com does not offer these results, though, as a reflection of a more traditional one, nor does the m-w thesaurus.