"borescope." YourDictionary, n.d. Web. 05 December 2018. <https://www.yourdictionary.com/borescope>.
borescope. (n.d.). Retrieved December 05th, 2018, from https://www.yourdictionary.com/borescope
An opticalinstrument used for seeing inside tight spaces, consisting of a rigid or flexible tube with an optical relay inside so that the view through a lens or window at one end of the tube may be seen from a lens or eyepiece in the opposite end of the tube.
English Wiktionary. Available under CC-BY-SA license.