Translate into same language with dictionary popup
Imagine kids can expand their native language vocabulary quickly by using your vocabulary service, that would be wonderful.
Another reason, my native language is Chinese. The huge disparity of Latin and Asian language root always sucks in cross translation, and often the multiple meaning and usage of same words is drastically different in both culture, we almost need to double check in English to English dictionary. English to Chinese translation only help us build up basic vocabulary only. People in same situation will also benefit in English to English translation.
Readlang is by far the best service I found, better than Dulingo, Lingua.ly, really wish this could be implemented. Thank you :)
Monolingual definitions are now available on Readlang.
See how it works here: http://blog.readlang.com/2015/09/30/monolingual-mode-arrives-to-readlang.html