Tatkal is a Sanskrit word meaning Instant. Indian Railways offers a special reservation scheme called Tatkal. The idea is to help passengers book tickets during an emergency. The railways earn a premium on such Tatkal quota tickets. The Tatkal System also applies in Passport, Telephone, Water & Electricity connection, etc.
Your vote on this answer has already been received
Without delay. Usually, the word will be for issue of passport., Passport will be issued in general for about 45 days, but in tatkal scheme, within 3 days., so urgently, necessity is the mother of all inventions.