Connecting two Android applications

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http://stackoverflow.com – I was developing a dictionary app which could be accessed in a third party app. The basic idea is that whenever you are using any app(say viewing a webpage or messaging) and you want to know the meaning of any word then all you have to do is select that word and share it to my app. I have developed most of the code but the thing is I am not able to get a mechanism to share the word from the third party app(say a messenger app)into my app. Whenever you select a word it should give you an option called "share to dictionary" and this should redirect you to the dictionary(my app) and display the (HowTos)