Have you just encountered an unfamiliar word in an Android app? By default, Google’s mobile OS doesn’t have a built-in/preinstalled/native dictionary, so you can’t look up the meaning of the word just yet. You’d have to find and download a dictionary/thesaurus app from the Play Store first. One of the better choices there is WordLookup, a pop-up tool that lets you easily look up a definition without needing to leave the app you’re currently using.
You can think of WordLookup for Android as if it were the popular extension for the Chrome browser, Google Dictionary, that quickly displays the meaning of a word with just a simple double-click highlighting. But since Android smartphones and other devices don’t usually have a mouse pointer for double-clicking, WordLookup requires users to tap-and-hold on a word to highlight it, tap the button for sharing, and select WordLookup on the list. You aren’t exactly sharing it, as the action will just invoke the pop-up dialog box that displays the definition of the selected word. (Using the sharing menu is the developer’s workaround for his niftly little app, given that it’s currently the most convenient method in Android for quick definition lookup.) The pane that appears is only temporary, unobtrusive, and fades into oblivion after a short while.
WordLookup is currently compatible with the native Android browser for versions Ice Cream Sandwich and later, mobile Google Chrome, Gmail, Google Reader, Pulse, and many more apps that allows text highlighting and has the sharing button.
Requring Android 2.1 and up, WordLookup requires an active Internet connection to retrieve definitions via the Wordnik API. Customizations include adjusting the number of definitions/meanings to be displayed on the pop-up dialog box, how long the box stays displayed, and text-to-speech option, with more features to follow (including offline dictionaries and use of other sources).
If you wan’t a full-fledged offline dictionary in your Android device, I recommend the Merriam-Webster app.