Requesting recommendation for J->J dictionary app and/or website

[pgoonghang]

I’m looking for a Japanese to Japanese dictionary for language learners. I’d say I’m at a lower intermediate level. For example, I can understand the definitions on the NHK Easy News site pretty well, even though they’re given in Japanese.

Is there a website or, even better, and iphone app that does the same?

[Kumirei]

From the resource list:

Japanese to Japanese:

• Goo

• KotoBank.jp
• Weblio
• ALC
• Zokugo-dict Japanese urban dictionary