Wikipedia is a free, multilingual open-collaborative online encyclopedia created and maintained by a community of volunteer editors using a wiki-based editing system.
Wikipedia offline is a paid service for Android version and a free service for iOS version.
Android: need to buy OsmAnd+ application (or OsmAnd Unlimited in-app for Free version) or OsmAnd live subscription.
iOS: Menu → Plugins → Wikipedia
In order to download Wikipedia articles for the country for using it Offline:
Android: Menu → Download maps → Regions
iOS: Menu → Maps & Resources → Worldwide
You can check which Wikipedia files you already have downloaded:
Android: Menu → Download maps → Wikipedia
iOS: Menu → Maps & Resources → Local
Next, you can enable Wikipedia POI on the map:
Android: Menu → Configure map → Show → Wikipedia
iOS: Menu → Map → POI Overlay → Wikipedia
In OsmAnd you can find Wiki-articles on the map by searching the menu in the left corner of the screen.
In Categories search menu you need to choose Wikipedia category:
Android: Search → Categories → Wikipedia
iOS: Search → Categories → Wikipedia
You see all the nearest Wikipedia articles. You can click to "Show Wikipedia on the map" for showing POI on the map:
In OsmAnd for Android, you can select languages for Wikipedia articles on the map:
Android: Menu → Configure map → Show → Wikipedia → Language
In OsmAnd for iOS, you can click on Wikipedia POI on the map, click to description and select an available language for Wikipedia article.
Enjoy Wikipedia on the map in your trip.