adverbial N2 common casual

ろくに〜ない — not properly ~

ろくに〜ない・ろくに

Meaning

not properly / not even adequately ~ — something is done so little or so poorly it doesn't reach a decent level, with a tone of complaint

忙いそがしくて、ろくに食事しょくじもしていない。

I've been so busy I haven't even eaten properly.

Attaches to	Form	Example
ろくに + negative predicate	ろくに + 〜ない	ろくに寝ねていない / ろくに話はなせない

彼かれはろくに調しらべもせずに、結論けつろんを出だした。

He reached a conclusion without even looking into it properly.

緊張きんちょうして、ろくに挨拶あいさつもできなかった。

I was so nervous I couldn't even greet them properly.

ろく (碌) means 'satisfactory / decent', so ろくに〜ない is 'not to a decent degree'. It implies the speaker thinks the level fell short of what it should be.

Jengo shows ろくに〜ない the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.

Sources Compiled from published Japanese grammar references.