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"All my technical advices in this forum must be consulted with and approved by a local registered professional engineer before implementation" - Mohammed Samad (Linkedin Profile: http://www.linkedin.com/in/msamad)
Both of What have been mentioned above are correct, but it depends on where you've found this term.... look! maybe it stands for somethings else,,, for instance, the "CT" stands for Current Transformer in electrical engineering and stands for Coiled Tubing when referring to Petroleum engineering....