Most travelers are likely to be spending some time in places where foreign languages are spoken, and there are some apps out there that make learning and referencing as you go extremely easy. Here are a few of them.
Duolingo probably won’t teach you a new language from scratch, but the free app will help you freshen up on one or work on adding in some new vocab words. Using the app is basically like playing a game, you have to make through each level before advancing on to the next.
HelloTalk looks and functions a lot like Whatsapp, except that the purpose of it is to link up people with different native tongues to practice speaking to one another.
MindSnacks teaches vocab and grammar through timed games. The app is free but offers access to more games if you upgrade.
Memrise had vocabulary lessons for every language out there, and beyond the standard textbook words, it also gives you “naughty” words and things like translations from Harry Potter.
Fluent Panda gives you small tasks to accomplish, and upon do you collect leaves to feed your virtual panda. The panda grows as your skills do.