Hi,
I am developing an interactive English vocabulary learning app. In order that the built-in vocab quiz function will work, my app needs offline access to an English-English dictionary and an English idiom dictionary. Does anyone know any such dictionary resources which I can use for free or at a small fee? I need the headwords with definitions and, if available, the examples.
My app is not for profit and will be open to public use for free, so I would prefer free resources if available. I will be very grateful indeed if colleagues would point me to the right direction. Thanks!