captcha

/K AE1 P CH AH0/
noun
  1. 1

    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 he/she is a human and not a computer program.

Source: https://en.wiktionary.org/wiki/CAPTCHA, https://en.wiktionary.org/wiki/captcha