Definition
DELAY COUNTDOWN TIMER (DCT)
The display of the delay that must be absorbed by a flight prior to crossing a Meter Reference Element (MRE) to meet the TBFM Scheduled Time of Arrival (STA). It is calculated by taking the difference between the frozen STA and the Estimated Time of Arrival (ETA).
Source: FAA Pilot/Controller Glossary (verbatim from the Federal Aviation Regulations).