noun: A computerized test requiring the human user to perform a task deemed to be difficult to automate, such as entering a displayed series of distorted characters or describing images, to demonstrate that they are a human and not a computer program.
noun: Alternative letter-case form of CAPTCHA [A computerized test requiring the human user to perform a task deemed to be difficult to automate, such as entering a displayed series of distorted characters or describing images, to demonstrate that they are a human and not a computer program.]
