Definition of "hydrophone" [hydrophone]

• An electrical instrument for detecting or monitoring sound under water. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "During some types of gynaecological examination, researchers have inserted a tiny microphone, called a hydrophone, into the uterus, enabling them to hear what the foetus can hear."
• "They used what's called a hydrophone to eventually get Humphrey out of that area."
• "A underwater "hydrophone" recorded the sound, and it was synched with the video."