You can find a mobile version of the Wits catalogue here.
The Merriam Webster medical dictionary is now available on your mobile device. The National Library of Medicine (NLM) has made this available via MedlinePlus Mobile. This includes sound clips so you can hear how to pronounce the term.
Here are a few suggestions for apps you might find useful. The links will direct you to where you can download the app. You will need to download these onto your mobile device