I would recommend either 1. Tabers or 2. Dorlands illustrated dictionary 32nd Dorlands is much more exhaustive and frankly I prefer Dorlands. I had bought Tabers mobile dictionary 1 year ago thinking it was cheaper than Dorlands dictionary. It is not so. Tabers purchase limits you to 1 year subscription for both mobile + web (a fact I didnt know until it expired a few days ago.) Besides being restricted to one iPad + one phone (plus web access) My mistake : I had thought it was a life time subscription, with the web access being available for 1 year. Pros of Dorlands 1. one time purchase 2. I have two iPads, one phone, one ipod touch...my sister has one ipad, one iphone...So We share the ID, and thus the app is available everywhere for use. ( cost / device becomes much cheaper this way.) Dorlands, if you are reading this. Dont get any ideas and go the subscription style. I will be recommending you to many others. Content wise, if money is not a problem, Get Tabers too. Some definitions are easier to understand in one app, and vice versa.