There's a new iOS app, called Meanings, that lets people point a video stream toward any word to retrieve a definition.
Using image-processing OCR technology (or a "pseudo augmented reality technique" - as the app's developer called it) that has long existed in popular PDF readers, the new app can define any word in a printed text document.
Of course, the result may not be always accurate, especially if it's a custom or non-standard font, but the app should still save users time from having to manually type unknown words into a dictionary.
So - how does it work? Load the app and point the video stream at any printed document. Once in focus, tap a word. The app will immediately serve up a definition. If it doesn't, just try adjusting the distance between the device and the word.
Definitions will come from the built-in iOS Dictionary or Google and Wikipedia (if connected to the Internet). Other features include a night mode and the ability to copy a word to the clipboard.