Practice JLPTHow to tell them apart
ろくに〜ない judges the quality or adequacy of an action — the subject does it, but poorly or insufficiently (ろくに勉強もしない). 滅多に〜ない judges frequency — the event almost never happens at all (滅多に起きない). Swapping them is wrong because a rare event isn't necessarily done poorly, and a poorly-done action isn't necessarily rare.
- ろくにない Use ろくに〜ない when someone does an action but does it poorly, inadequately, or half-heartedly.
- 滅多にない Use 滅多に〜ない when something happens so rarely that it is almost never seen or experienced.
| Grammar point | Meaning | JLPT level |
|---|---|---|
| ろくにない rokuninai | Not properly; not well; barely; hardly | N3 |
| 滅多にない ninai | Seldom; rarely; hardly ever | N1 |
ろくにない rokuninai
Not properly; not well; barely; hardly
Not sufficiently; not satisfactorily; not properly; not well; hardly | A structure that is used to indicate that something animate does not or cannot do something satisfactorily/sufficiently/properly.
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せっかくデパートまで買い物に出かけたのに、買い物中気分が悪くなってろくに買い物もせずに帰って来た。
I went shopping, and got as far as to a department store, but I came home without even shopping properly because I felt sick while shopping.
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ろくに勉強もしないで試験を受けたので、全然出来なかった。
I took the exam without studying properly, so it was a disaster (literally: I couldn't do well at all).
滅多にない ninai
Seldom; rarely; hardly ever
Rarely; seldom; hardly; almost never | A structure that indicates extremely low frequency.
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この辺りでは地震は滅多に起きない。
Earthquakes seldom occur in this area.
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大学時代の同級生とは滅多に合えない。
I can hardly ever see my college classmates.
ろくにない and 滅多にない are JLPT N3–N1 grammar points that Japanese learners often mix up. This page compares them side by side — meanings, usage and example sentences — so you can tell them apart.