This app was mentioned in 3 comments, with an average of 1.67 upvotes
I use Norsteds for android (although for different second language but I guess English will be even better), I'm very satisfied with it. It's on google play. It's pricey though.
I haven't tried the mobile app of this, but the web version is the greatest dictionary out there, if you have the money. Android: https://play.google.com/store/apps/details?id=se.norstedts.engelskaordbokpro, iOS: https://itunes.apple.com/se/app/norstedts-engelska-ordbok-pro-2-0/id850258288?mt=8
The web version is found at https://ne.ord.se/ordbok/svenska/en-pro/s%C3%B6k/
Norstedts is the one I bought for my partner in the app version. She says it's great.
For less popular languages, you often have to go outside the English publishers like Oxford and Collins, and instead look at what people from those countries use to learn English. For Norwegian, I went with the Ordnett one.