This is probably my most wanted feature. Often times i see a word during my Japanese immersion that i've learned before, but either i don't remember it or it takes me a while to remember. Or the other way around, i'm trying to say a word in Japanese that I know i've learned but it doesnt spring to mind fast enough. So i look it up in the dictionary and then go, "ohhhh yeah, of course, that's what it meant/that's how you say it". I'm sure many can relate.
Here's where my idea comes in. Right now, what i do is manually lower the mastery of the term in order to mark it down and hopefully make it so that Renshuu makes me study it more. Alternatively, i can add it to a list of terms i need to study more. Neither of these options is really satisfying, though.
My idea would be a "study more" button in the dropdown menu next to a term in the dictionary, which would function basically like getting the answer wrong in a quiz : Make you study it the next few days, maybe knocking down the mastery a bit as well.