Couplant 1 : A material (usually a liquid) used between ultrasonic transducer and the test specimen to conduct ultrasonic energy between them. (RP 5A5)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}