s (of facilities such as telephones or lavatories) unavailable for use by anyone else or indicating unavailability; (`engaged' is a British term for a busy telephone line)
How to Spot a Liar (With Help From the CIA) Philip Houston is regarded to be one of America’s top lie-catchers. In his 25 years as a CIA operative, he interrogated or interviewed thousands of individuals, developing “detection of deception” techniques that are still in use today.
July 19, 2013 - Forbes