a multi platform dictionary app

Hey, i'm just an ordinary student, currently on highschool, got ZEROO knowledge on how to build an "app" and I would like to get an idea or at least an easy way to do it, any pages or programs suggested?
 
The main idea for this app is to search a word with suggestions below, (like when you are searching something on google) and then have the definition of the word you wanted.
 
Thanks a lot.
Luis.