If that’s the case, then it depends on what type of Kindle device it is. I believe the Kindle Fire can sideload apps but the Paperwhite cannot.
If you have the Kindle Fire, then it should just be a matter of acquiring the apk file of the look-up app you want and installing it.
I haven’t used this sort of thing in a while but I’ve gotten a lot of use out of Kaku. It’s also quite possible there are other apps out there that are just as good at this point.
If you need assistance getting the apk file I’m quite knowledgeable about that as well.