If you're not 'down with the cool kids' (a phrase which itself - ironically - declares me as NOT one of the cool kids!) then you may need some help deciphering slang you hear in town and online in chat rooms. Which is where the Urban Dictionary comes in. It's a crowd-sourced (and lightly curated) repository of slang and miscellany and... hard to access on mobile, since the web site's not responsive. So a client is needed and this is where this new UWP app for Windows 10 Mobile comes in.