Honestly, I write it captcha most of the time. Properly stylized CAPTCHA, this machine-defeating checking mechanism (created in 2000, named in 2003) seems like a portmanteau of "capture" and "gotcha", alluding to its identification of bots online. While that was indeed a major influence on the development of the word, CAPTCHA is actually a loose acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart", a Turing Test being a way of telling apart humans and robots. Obviously the acronym is a bit messed up and fitted to look how the creators wanted it to; if it conformed to standards of capitalization, the CAPTCHA should actually be a CAPTTTCHA. When Google invented a CAPTCHA system in 2007 to simultaneously digitize books and check for bots, they named it the reCAPTCHA, which makes the CAPTCHA a word so old that it is already the etymon of another.
Adam Aleksic, a leading contender for valedictorian of his high school, is a 215-month-old boy with disturbing interests in etymology, vexillology, geography, and law. Adam would like to one day visit Tajikistan and probably isn't spying for the Uzbek government.
The Etymology Nerd