You can increase your vocabulary with a number of apps. Here are some websites & apps:
Vocabulary.com - This software offers individualized tests and study resources to aid in vocabulary development.
https://www.vocabulary.com/
Quizlet is a flashcard program that lets you create your own vocabulary sets or use sets that others have already developed.
https://quizlet.com/
Merriam-Webster Dictionary - The Merriam-Webster Dictionary app contains a function that allows users to learn a new word each day in addition to providing word meanings.
https://www.merriam-webster.com/games
Word of the Day: To help you build your vocabulary, this app delivers you a new word and its description each day.
https://play.google.com/store/apps/details?id=helium.wordoftheday.learnenglish.vocab&hl=en&gl=US
Elevate - Elevate is an app that provides a variety of games and challenges to help you sharpen your cognitive abilities and vocabulary.
https://play.google.com/store/apps/details?id=com.wonder&hl=en&gl=US
Duolingo – Although primarily created for language instruction, Duolingo can also aid in expanding your vocabulary.
https://www.duolingo.com/
These are but a few examples of the numerous apps that are available to aid in vocabulary development.