Best Dictionary Apps? for Windows 8?

Anyone here have a favorite dictionary app for Windows 8? and/or thesaurus?
I know that the Windows App store has user reviews. But I thought I'd ask among the serious word nerds.
When I'm working on my fiction writing, I try to keep myself from getting on-line. I have the OED on my laptop , but that's sometimes overkill. I'm rather partial to the American Heritage Dictionary, but the software I had wouldn't load/run on Windows 8.

On-line, I tend to go to OneLook, & from the list go to AHD, Merriam-Webster, or Collins. I like Thesaurus.com.
But what works on-line doesn't necessarily mean the app is good or useful.

Any thoughts?