Deuljwi (들쥐) meaning: why a wild mouse isn't just 쥐

If you watched the Netflix thriller everyone’s calling Mousetrap, you may have noticed the Korean title doesn’t say “trap” anywhere. It’s 들쥐. The series topped Netflix’s non-English TV chart in early September 2026, and English coverage notes it’s based on a webtoon called “Field Mouse”. So the title you know and the title on the screen don’t line up, and the Korean one is a small word-building lesson hiding in plain sight.

That’s the part worth ten minutes. The show is only the way in.

What does 들쥐 (deuljwi) mean?

It means a field mouse, a wild one, as opposed to the house mouse. The Standard Korean Dictionary (표준국어대사전) lists 들쥐 as an everyday word for 멧밭쥐, a field mouse species (표준국어대사전 entry for 들쥐). Split it up and you get 들- plus 쥐 (jwi, “mouse” or “rat”). The English title picked a trap; the Korean one picked an animal.

The folktale behind the series helps explain why the word fits. The director has said the work is motivated by the folktale of the fingernail-eating rat, in which a rat that eats a person’s fingernails becomes human. That’s all the plot this article needs.

What does the prefix 들- do?

It adds “growing wild” to an animal or plant noun. The dictionary has 들- as a prefix with exactly that sense, and a second, unrelated one for some verbs (표준국어대사전 entry for the prefix 들-). Its example words include 들개 (a stray dog) and 들가뢰, a kind of insect.

Plain noun	With 들-	Meaning
개 (gae)	들개 (deulgae)	a stray dog, per the dictionary
쥐 (jwi)	들쥐 (deuljwi)	a field mouse

The mental model: the plain noun is the default animal you meet indoors or on a farm, and 들- moves it outdoors and out of anyone’s care. Notice that the English glosses don’t match one for one. “Stray dog” isn’t “wild dog,” and the dictionary’s own wording for the prefix is the broader “growing wild.” If you’re reading, trust the prefix to tell you the animal lives untended; for the exact sense of a given word, check the entry.

Is every 들 the same 들?

No, and this is where learners trip. There are at least three 들 you’ll meet, and they don’t share a job:

• The prefix 들-, above: wild, on animal and plant nouns.
• The noun 들, a field. 들꽃 is defined as 들에 피는 꽃, “a flower that blooms in the fields,” and the same entry lists 야생화 as a synonym (표준국어대사전 entry for 들꽃). The meaning lands in the same place as the prefix, but the dictionary frames this one as “field.”
• The plural -들, as in 사람들, which sits at the end of a word and has nothing to do with wildness. If that one still feels slippery, we sorted out the plural 들 and its adverb cousin in a separate post.

A quick check helps. If 들 comes first and the rest is an animal or plant, think “wild.” If it comes last, think plural.

Which 쥐 expressions is it safe to use?

One 쥐 expression is worth knowing: 쥐도 새도 모르게 (“without even a mouse or a bird knowing”) means doing something secretly, with nobody noticing. It’s listed among rat expressions in KoreanClass101’s lesson on Korean rat idioms. That’s a language-school source, not a dictionary entry. A search of the Standard Korean Dictionary for the exact phrase returned nothing, so treat the meaning as well attested in teaching material but not confirmed against an official source. Here’s the honest answer: I’ll only vouch for one in this post. 쥐도 새도 모르게 (“without even a mouse or a bird knowing”) means doing something secretly, with nobody noticing, and it’s listed among rat expressions in KoreanClass101’s lesson on Korean rat idioms. That’s a language-school source, not a dictionary entry. I looked for the expression in the Standard Korean Dictionary and Urimalsaem and didn’t find it there, so treat the meaning as well attested in teaching material but not confirmed against an official source.

Other 쥐 sayings circulate widely, but I couldn’t confirm their exact wording and meaning against a primary source, so I’ve left them out. Better a short list you can trust than a long one you can’t.

What to take from this

• 들쥐 is a field mouse, and the Korean title points at the animal, not the trap.
• 들- before an animal or plant noun adds “growing wild”; 들개 is the dictionary’s example.
• Prefix 들-, noun 들 (field) and plural -들 are three different things. Position is the quick test.
• Check a new compound’s exact sense in the dictionary before reusing it; the prefix gives you the direction, not the whole meaning.

Noticing a word like this once is easy. Meeting it again inside a sentence at listening speed is the hard part, and it’s the gap behind how I improved my Korean listening. up103 builds listening practice from the notes you already keep: Claude reads the notes and writes the texts, and ElevenLabs speaks them. It’s free during the beta at app.up103.com.

— 민지, up103